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Reason under uncertainty
Compute with random variables, justify statistical inference from data, and model systems that evolve at random.
- Calculus one page Limits, derivatives, integrals, sequences, and series in one variable. Open
- Probability Theory 8 chapters · 175 exercises Random variables, conditioning, expectation, the laws of large numbers, and the central limit theorem. Start Chapter 1, Probability Spaces and Counting
- Mathematical Statistics 13 chapters · 262 exercises Estimation, likelihood, testing, regression, experimental design, and Bayesian inference. Start Chapter 1, Statistical Models, Parameters, and Identifiability
- Stochastic Processes one page Markov chains, Poisson processes, renewal theory, queues, and martingales. Open
Optimize decisions
Set up linear, convex, dynamic, and combinatorial decision problems, solve them, and read what the solution says.
- Linear Algebra one page Vectors, matrices, rank, orthogonality, eigenvalues, and matrix decompositions. Open
- Multivariable Calculus 9 chapters · 184 exercises Gradients, Jacobians, Hessians, multiple integrals, and vector calculus. Start Chapter 1, Vectors, Curves, and Geometry in Space
- Continuous Optimization 10 chapters · 202 exercises Linear and convex optimization, duality, KKT conditions, and the algorithms that solve them. Start Chapter 1, Optimization Models and Feasible Geometry
- Dynamic Programming and Optimal Control 10 chapters · 196 exercises Bellman recursions, Markov decision processes, and optimal control. Start Chapter 1, Sequential Models and Sufficient State
- Discrete Optimization 10 chapters · 196 exercises Networks, matching, integer programming, branch-and-bound, and cutting planes. Start Chapter 1, Discrete Models, Encodings, and Complexity
Think strategically
Model strategic interaction, compute equilibria, design auctions and mechanisms, and shape what others learn.
- Discrete Mathematics 8 chapters · 195 exercises Logic, proof, counting, recurrences, graphs, and relations. Start Chapter 1, Logic and the Language of Proof
- Probability Theory 8 chapters · 175 exercises Random variables, conditioning, expectation, the laws of large numbers, and the central limit theorem. Start Chapter 1, Probability Spaces and Counting
- Continuous Optimization 10 chapters · 202 exercises Linear and convex optimization, duality, KKT conditions, and the algorithms that solve them. Start Chapter 1, Optimization Models and Feasible Geometry
- Game Theory 10 chapters · 194 exercises Nash equilibrium, dynamic and repeated games, incomplete information, auctions, and cooperative games. Start Chapter 1, Strategic Form, Best Responses, and Dominance
- Information Design 3 chapters · 65 exercises Signaling, cheap talk, the value of information, Bayesian persuasion, and information design. Start Chapter 1, Beliefs as the Object of Choice
Work with Brownian motion and stochastic calculus
Handle Brownian motion, Itô's formula, and stochastic differential equations on a measure-theoretic footing.
- Probability Theory 8 chapters · 175 exercises Random variables, conditioning, expectation, the laws of large numbers, and the central limit theorem. Start Chapter 1, Probability Spaces and Counting
- Stochastic Processes one page Markov chains, Poisson processes, renewal theory, queues, and martingales. Open
- Real Analysis 8 chapters · 187 exercises Rigorous limits, continuity, differentiation, Riemann integration, and metric spaces. Start Chapter 1, Completeness of the Real Numbers
- Measure Theory 10 chapters · 185 exercises Sigma-algebras, measures, Lebesgue integration, and the convergence theorems. Start Chapter 1, Sigma-Algebras and Measures
- Measure-Theoretic Probability 10 chapters · 197 exercises Probability on measure spaces, conditional expectation, and martingale convergence. Start Chapter 1, Random Elements, Laws, and Expectation
- Stochastic Calculus one page Brownian motion, quadratic variation, the Itô integral and formula, and stochastic differential equations. Open
Prove things in analysis
Carry rigorous limits from the real line through Lebesgue integration to Banach and Hilbert spaces.
- Calculus one page Limits, derivatives, integrals, sequences, and series in one variable. Open
- Real Analysis 8 chapters · 187 exercises Rigorous limits, continuity, differentiation, Riemann integration, and metric spaces. Start Chapter 1, Completeness of the Real Numbers
- Measure Theory 10 chapters · 185 exercises Sigma-algebras, measures, Lebesgue integration, and the convergence theorems. Start Chapter 1, Sigma-Algebras and Measures
- Functional Analysis 10 chapters · 197 exercises Banach and Hilbert spaces, bounded operators, duality, and compactness. Start Chapter 1, Normed Spaces and Completeness
Model change with differential equations
Solve and analyze ordinary and partial differential equations, and compute with them reliably.
- Calculus one page Limits, derivatives, integrals, sequences, and series in one variable. Open
- Linear Algebra one page Vectors, matrices, rank, orthogonality, eigenvalues, and matrix decompositions. Open
- Differential Equations 8 chapters · 160 exercises Ordinary differential equations, linear systems, stability, and phase analysis. Start Chapter 1, Differential Equations as Models
- Multivariable Calculus 9 chapters · 184 exercises Gradients, Jacobians, Hessians, multiple integrals, and vector calculus. Start Chapter 1, Vectors, Curves, and Geometry in Space
- Partial Differential Equations 10 chapters · 185 exercises First-order equations, the heat, wave, and Laplace equations, characteristics, and energy methods. Start Chapter 1, PDE Models and Classification
- Numerical Analysis 10 chapters · 216 exercises Error, floating point, root finding, interpolation, quadrature, and numerical linear algebra. Start Chapter 1, Floating-Point Arithmetic and Conditioning
Write proofs about structure
Read and write proofs about groups, rings, fields, and quotient structures.
- Discrete Mathematics 8 chapters · 195 exercises Logic, proof, counting, recurrences, graphs, and relations. Start Chapter 1, Logic and the Language of Proof
- Abstract Algebra one page Groups, rings, ideals, quotients, fields, and algebraic proof. Open
Design a rocket
Size a two-stage launcher for a stated payload and orbit, and defend every number.
- Calculus one page Limits, derivatives, integrals, sequences, and series in one variable. Open
- Rocket Science 12 chapters · 260 exercises Size a two-stage launcher from the rocket equation to a converged design. Start Chapter 1, Momentum and the Rocket Equation
Speak everyday Italian
Handle everyday exchanges in Italian at level A2.
- Italian A2 one page Everyday Italian to level A2, from greetings and routines to travel, appointments, and short writing. Open
Something else
All 23 courses
Foundations
- Abstract Algebra one page Groups, rings, ideals, quotients, fields, and algebraic proof.
- Calculus one page Limits, derivatives, integrals, sequences, and series in one variable.
- Discrete Mathematics 8 chapters · 195 exercises · Draft Logic, proof, counting, recurrences, graphs, and relations.
- Linear Algebra one page Vectors, matrices, rank, orthogonality, eigenvalues, and matrix decompositions.
Analysis and equations
- Differential Equations 8 chapters · 160 exercises · Draft Ordinary differential equations, linear systems, stability, and phase analysis.
- Functional Analysis 10 chapters · 197 exercises · Draft Banach and Hilbert spaces, bounded operators, duality, and compactness.
- Measure Theory 10 chapters · 185 exercises · Draft Sigma-algebras, measures, Lebesgue integration, and the convergence theorems.
- Multivariable Calculus 9 chapters · 184 exercises · Draft Gradients, Jacobians, Hessians, multiple integrals, and vector calculus.
- Numerical Analysis 10 chapters · 216 exercises · Draft Error, floating point, root finding, interpolation, quadrature, and numerical linear algebra.
- Partial Differential Equations 10 chapters · 185 exercises · Draft First-order equations, the heat, wave, and Laplace equations, characteristics, and energy methods.
- Real Analysis 8 chapters · 187 exercises · Draft Rigorous limits, continuity, differentiation, Riemann integration, and metric spaces.
Probability and statistics
- Mathematical Statistics 13 chapters · 262 exercises · Draft Estimation, likelihood, testing, regression, experimental design, and Bayesian inference.
- Measure-Theoretic Probability 10 chapters · 197 exercises · Draft Probability on measure spaces, conditional expectation, and martingale convergence.
- Probability Theory 8 chapters · 175 exercises · Draft Random variables, conditioning, expectation, the laws of large numbers, and the central limit theorem.
- Stochastic Calculus one page Brownian motion, quadratic variation, the Itô integral and formula, and stochastic differential equations.
- Stochastic Processes one page Markov chains, Poisson processes, renewal theory, queues, and martingales.
Optimization, games, and information
- Continuous Optimization 10 chapters · 202 exercises · Draft Linear and convex optimization, duality, KKT conditions, and the algorithms that solve them.
- Discrete Optimization 10 chapters · 196 exercises · Draft Networks, matching, integer programming, branch-and-bound, and cutting planes.
- Dynamic Programming and Optimal Control 10 chapters · 196 exercises · Draft Bellman recursions, Markov decision processes, and optimal control.
- Game Theory 10 chapters · 194 exercises · Draft Nash equilibrium, dynamic and repeated games, incomplete information, auctions, and cooperative games.
- Information Design 3 chapters · 65 exercises · In progress, 3 of 10 chapters Signaling, cheap talk, the value of information, Bayesian persuasion, and information design.
Engineering
- Rocket Science 12 chapters · 260 exercises · Draft Size a two-stage launcher from the rocket equation to a converged design.
Languages
- Italian A2 one page Everyday Italian to level A2, from greetings and routines to travel, appointments, and short writing.
No course matches.
How the courses build on each other
Change To Accumulation Full Course Manual
Course Promise
After the course, the learner can use limits, derivatives, integrals, and the Fundamental Theorem to reason about local change, accumulated change, approximation, optimization, and method choice. The learner should be able to teach another learner when a problem asks for a limit, derivative, definite integral, antiderivative, or theorem bridge.
Course Spine
- Start state: The learner can substitute into functions, manipulate basic algebra, read graphs informally, and track units, but does not yet separate value from nearby behavior, average rate from instantaneous rate, or accumulated amount from endpoint value.
- Terminal capability: The learner can decide whether a prompt asks for a limit, continuity check, derivative, base derivative or antiderivative rule, tangent approximation, optimization argument, Riemann-sum/integral setup, FTC bridge, or mixed method-choice explanation.
- Pillar points: function change and units; limit/value/continuity; derivative definition and derivative rules; base derivative and antiderivative rules for powers, trigonometric functions, exponentials, and logarithms; local approximation and optimization; accumulation, definite integral, and Fundamental Theorem; method-choice synthesis.
- Chapter progression: The course starts with function change, sharpens that into limit language, turns shrinking average rates into derivatives, uses derivative tools for local models and optimization, turns many small changes into integrals, then ends by connecting rate and total through the FTC.
- End evidence: The learner solves mixed Calculus I prompts, shows the setup before computing, states units or interpretation, repairs common false methods, and teaches why the chosen tool matches the job.
Chapter Map
| Chapter | Starts from | Unlocks | Key points | Ends when learner can | Feeds into |
|---|---|---|---|---|---|
| 1. Functions, Limits, And Continuity | Algebraic functions, graph reading, and units | Describing change and local behavior separately from exact value | input/output, average rate, limit, value, continuity conditions, removable/jump/infinite breaks | compute and interpret average rate, state a limit and value separately, and diagnose a continuity failure | derivative definition as a limit of average rates |
| 2. Derivatives And Rate Rules | Limits and average rate | Instantaneous rate and symbolic rate tools | difference quotient, derivative definition, differentiability, power rule, trigonometric/exponential/logarithmic derivative rules, product rule, quotient rule, chain rule, higher derivatives, units | derive a derivative from first principles for a simple function, apply base and structural rules with meaning, and catch false shortcut rules | local linear models, optimization, MVT, shape, and rate-to-total reasoning |
| 3. Local Models, MVT, Shape, And Optimization | Derivative as slope/rate | Approximation, guaranteed rate statements, graph shape, and best local choice | tangent line, linearization, differential, critical point, endpoint test, first/second derivative signs, Mean Value Theorem, related rates setup | build a local estimate, explain an MVT guarantee, classify shape, and solve an optimization problem with candidate comparison | accumulation and method-choice contrasts |
| 4. Accumulation And FTC | Rates, units, and local change | Total change from many small pieces | Riemann sum, definite integral, signed area, net change, base antiderivative rules, basic substitution, antiderivative, FTC Part 1 and Part 2 | set up a sum/integral, interpret signed area, and use base antiderivatives, substitution, plus both directions of the FTC | final mixed method choice |
| 5. Method Choice Synthesis | All previous chapters | Choosing the right calculus object before computing | job-to-tool table, prompt cues, units, graph/procedure contrasts, proof/counterexample tasks | explain why the selected method fits and why a tempting alternative does not | later calculus or applied modeling |
Detailed Knowledge Point Manual
Function Change And Average Rate
Hook: Calculus begins when the learner stops asking only “what is the value?” and starts asking “how is the output changing as the input changes?”
Definition: For a function \(f\) , the average rate of change from \(a\) to \(b\) is:
It has output units per input unit.
Worked model: If \(V(t)\) is water volume in liters after \(t\) minutes, \(V(2) = 10\) , and \(V(7) = 35\) , then:
The rate is 5 liters per minute.
Classic trap: Reporting 5 without units or saying “liters” instead of “liters per minute.” Repair by naming output change, input change, then quotient units.
Exercise questions:
- Recall: What does average rate compare?
- Guided: If \(s(1) = 4\) meters and \(s(5) = 16\) meters, compute the average velocity.
- Independent: Give units for \([P(10) - P(4)] / (10 - 4)\) if \(P\) is dollars and input is days.
- Trap repair: A learner says the average rate is \(12\,\text{meters}\) . Fix the unit.
- Transfer: Invent a real function and an average-rate question.
- Teach-back: Explain why average rate is a quotient of two changes.
Limit, Value, And Continuity
Hook: Limits let the learner describe nearby behavior even when the value at the exact input is missing, weird, or different.
Definition: \(\lim_{x \to a} f(x) = L\) means the values of \(f(x)\) approach \(L\) as \(x\) gets close to \(a\) from both sides. It does not automatically mean \(f(a) = L\) .
Worked model: A graph has a hole at \((2, 6)\) and a filled dot at \((2, -3)\) . Then:
Continuity at \(x = a\) needs all three:
- \(f(a)\) is defined.
- \(\lim_{x \to a} f(x)\) exists.
- \(\lim_{x \to a} f(x) = f(a)\) .
Classic trap: Plugging in and stopping. Repair by asking: nearby behavior or actual value?
Exercise questions:
- Recall: What are the three continuity checks?
- Guided: For a hole at \((1, 4)\) and filled dot \((1, 9)\) , state the limit and value.
- Independent: Explain why a jump fails continuity.
- Trap repair: A learner says “the limit exists, so the function is continuous.” What condition might fail?
- Transfer: Sketch or describe a function where the value exists but the two-sided limit does not.
- Teach-back: Explain limit versus value to someone who wants to plug in immediately.
Derivative From First Principles
Hook: The derivative turns average rate into instantaneous rate by shrinking the input interval.
Definition: The derivative at \(a\) is:
The fraction is an average rate over a tiny interval; the limit is the tangent slope.
Worked model: For \(f(x) = x^{2}\) at \(x = 3\) :
For \(h \ne 0\) , the quotient is \(6 + h\) ; then the limit as \(h \to 0\) is 6.
Transfer models: If \(s(t)\) is position in meters, then \(s'(t)\) is instantaneous velocity in meters per second. If \(f(x) = |x|\) , then \(f'(0)\) does not exist because the left slope is -1 and the right slope is 1.
Classic trap: Setting \(h = 0\) before simplifying. Repair by saying \(h\) approaches zero but is not zero inside the quotient.
Exercise questions:
- Recall: Write the derivative definition at \(a\) .
- Guided: Start the difference quotient for \(f(x) = x^{2}\) at \(a = 2\) .
- Independent: Use first principles to find the derivative of \(f(x) = x^{2}\) at \(x = 1\) .
- Trap repair: Explain why \(\frac{0}{0}\) is not the final answer.
- Transfer: Explain why \(|x|\) has no derivative at 0.
- Teach-back: Explain secant slope becoming tangent slope.
Derivative Rules, Chain Rule, And Units
Hook: Derivative rules are not magic shortcuts; they preserve how change flows through sums, products, and layers.
Definitions: The product rule is \((fg)' = f'g + fg'\) . The chain rule is:
Worked model: If \(y = (x^{2} + 1)^{5}\) , the inside is \(g(x) = x^{2} + 1\) and the outside is \(u^{5}\) . Then:
If \(s(t)\) is meters, then \(s'(t)\) is meters per second. Units are part of the meaning.
Classic traps: Multiplying derivatives for a product; differentiating only the outside in a chain-rule problem.
Exercise questions:
- Recall: State the product rule.
- Guided: Identify inside and outside in \((3x - 1)^{4}\) .
- Independent: Differentiate \((x^{2} + 1)^{5}\) .
- Trap repair: Explain why \((fg)'\) is not \(f'g'\) .
- Transfer: Give units for the derivative of cost with respect to quantity.
- Teach-back: Explain the chain rule as layered change.
Base Function Derivative And Antiderivative Rules
Hook: Structural rules such as product rule and chain rule only work after the learner knows the base functions. A learner should not have to guess what happens to \(\sin(x)\) , \(\cos(x)\) , \(e^{x}\) , \(\ln x\) , or a power when a derivative or antiderivative appears.
Definition or form: The first-course base rule table is:
| Function family | Derivative rule | Antiderivative rule |
|---|---|---|
| Power, \(x^{n}\) | \(\frac{d}{dx} x^{n} = n x^{n-1}\) | \(\int x^{n} dx = x^\frac{n+1}{n+1} + C\) , for \(n \ne -1\) |
| Reciprocal, \(\frac{1}{x}\) | $\frac{d}{dx} \ln | x |
| Exponential, \(e^{x}\) | \(\frac{d}{dx} e^{x} = e^{x}\) | \(\int e^{x} dx = e^{x} + C\) |
| Sine | \(\frac{d}{dx} \sin x = \cos x\) | \(\int \sin x dx = -\cos x + C\) |
| Cosine | \(\frac{d}{dx} \cos x = -\sin x\) | \(\int \cos x dx = \sin x + C\) |
Trigonometric derivative rules assume angle input is measured in radians. Indefinite integrals require \(+ C\) because many functions differ by a constant but have the same derivative.
Worked model 1, derivative of \(\sin(x)\) :
At \(x = 0\) , the slope is \(\cos 0 = 1\) , so the sine curve is rising through the origin.
Worked model 2, product plus base rule: For \(f(x) = x^{2} \sin x\) ,
The first term changes the power while holding \(\sin x\) ; the second term changes \(\sin x\) while holding \(x^{2}\) .
Worked model 3, chain plus base rule: For \(g(x) = \sin(x^{2})\) ,
The outside derivative changes \(\sin\) to \(\cos\) ; the inside derivative contributes \(2x\) .
Worked model 4, antiderivatives:
Check by differentiating the answer. \(\frac{d}{dx}[-\cos x + C] = \sin x\) , and \(\frac{d}{dx}[x^{3} + \sin x + C] = 3x^{2} + \cos x\) .
Classic traps: Forgetting radians for trig rates; writing \(\int \sin x dx = \cos x + C\) with the wrong sign; forgetting \(+ C\) on indefinite integrals; differentiating \(\sin(x^{2})\) as only \(\cos(x^{2})\) and missing \(2x\) ; treating derivative and antiderivative rules as the same direction.
Exercise questions:
- Recall: State \(\frac{d}{dx} \sin x\) , \(\frac{d}{dx} \cos x\) , \(\int \sin x dx\) , and \(\int \cos x dx\) .
- Guided: Differentiate \(x^{2} \sin x\) .
- Independent: Differentiate \(\sin(x^{2})\) and name the inside derivative.
- Variation: Find \(\int (2x + \sin x) dx\) .
- Trap repair: A learner writes \(\int \sin x dx = \cos x + C\) . Diagnose and fix the sign.
- Transfer: Check an antiderivative by differentiating it back to the original function.
- Teach-back: Explain why \(+ C\) appears for indefinite integrals but not for ordinary derivative answers.
Linearization, Differentials, And Optimization
Hook: Derivatives support local estimates and best/worst decisions, but both require conditions.
Definition: Linearization at \(a\) is:
It is a local tangent-line model. Optimization on a closed interval checks endpoints and critical points.
Worked model: For \(f(x) = \sqrt{x}\) near \(a = 4\) , \(f(4) = 2\) and \(f'(x) = \frac{1}{2\sqrt{x}}\) , so \(f'(4) = \frac{1}{4}\) . Then:
Estimate \(\sqrt{4.2}\) : \(L(4.2) = 2 + 0.05 = 2.05\) .
For optimization, if \(f(x) = x^{2} - 4x\) on \([0, 5]\) , check \(f'(x) = 2x - 4 = 0\) , so \(x = 2\) , plus endpoints 0 and 5.
Classic traps: Treating local approximation as exact everywhere; forgetting endpoints.
Exercise questions:
- Recall: Write the linearization formula.
- Guided: Build \(L(x)\) for \(f(x) = x^{2}\) at \(a = 3\) .
- Independent: Find candidates for max/min of \(x^{2} - 4x\) on \([0, 5]\) .
- Trap repair: Why is solving \(f'(x)=0\) not enough on a closed interval?
- Transfer: Name one situation where a local estimate is useful but limited.
- Teach-back: Explain tangent-line approximation.
Riemann Sums, Definite Integrals, Signed Area, And FTC
Hook: Integrals turn many tiny rate pieces into total accumulated change.
Definitions: A Riemann sum has the form \(\sum f(x_i^\cdot ) \Delta x\) . A definite integral is the limit of such sums. If \(F'(x) = f(x)\) , then:
If \(A(x) = \int_a^{x} f(t) dt\) , then \(A'(x) = f(x)\) .
Worked model: If rate is \(r(t) = 3\) liters per minute for 4 minutes, the accumulated amount is \(3 \cdot 4 = 12\) liters. Units multiply: liters/minute times minutes equals liters.
For \(\int_0^{2} 3x^{2} dx\) , an antiderivative is \(x^{3}\) , so the integral is \(2^{3} - 0^{3} = 8\) .
For \(A(x) = \int_1^{x^{2}} \sin(t) dt\) , FTC plus chain rule gives:
Classic traps: Treating \(dx\) as decoration; making all area positive when the question asks net change; forgetting the chain-rule factor.
Exercise questions:
- Recall: What does a definite integral accumulate?
- Guided: Give units for \(\int_0^{5} r(t) dt\) when \(r\) is liters/minute.
- Independent: Compute \(\int_0^{2} 3x^{2} dx\) .
- Trap repair: Explain signed area versus total distance.
- Transfer: Differentiate \(\int_0^{x^{3}} \cos(t) dt\) .
- Teach-back: Explain the two directions of the Fundamental Theorem.
Method Choice Synthesis
Hook: A strong calculus learner chooses from the job, not from the most recent formula.
Decision procedure: Ask what the problem wants:
- nearby behavior: limit
- instantaneous rate or tangent slope: derivative
- local estimate: linearization
- maximum or minimum: optimization
- accumulated total: definite integral
- total from rate via antiderivative: FTC
- changing upper-limit accumulation: FTC plus chain rule
Worked model: A velocity graph question may ask for \(v(3)\) , acceleration at 3, displacement from 1 to 5, total distance, or a tangent estimate. The same representation supports different jobs.
Classic trap: Choosing the tool from the visual surface instead of the question verb.
Exercise questions:
- Recall: Which tool answers instantaneous rate?
- Guided: Sort “total change over an interval” into a tool.
- Independent: Sort six mixed prompts into limit, derivative, linearization, optimization, integral, or FTC.
- Trap repair: A learner sees a graph and says “take derivative” automatically. What should they ask first?
- Transfer: Rewrite a derivative prompt into an integral prompt.
- Teach-back: Explain job-first method choice.
Knowledge To Learn
Functions As Change
A function is a relationship between an input and an output. The learner must name input units, output units, interval, output change, and input change before calculating average rate. If \(V(t)\) is water volume in liters after \(t\) minutes, then \((V(7) - V(2)) / (7 - 2)\) is measured in liters per minute.
Classic trap: saying only the number and losing the unit meaning.
Limits And Continuity
A limit asks what the function approaches near an input, not necessarily what the function equals at that input. A hole at \((2, 6)\) with a filled dot at \((2, -3)\) gives \(\lim_{x \to 2} f(x) = 6\) and \(f(2) = -3\) .
Continuity at \(x = a\) needs three checks: \(f(a)\) is defined, the two-sided limit exists, and the limit equals the function value. A removable discontinuity fails equality; a jump fails the two-sided limit; an infinite break fails finite approach.
Classic traps:
- plugging in and stopping when the question asks nearby behavior
- saying a function is continuous because a limit exists
- ignoring one-sided disagreement
Derivative From First Principles
The derivative is the limit of average rates as an interval shrinks to one point:
For \(f(x) = x^{2}\) at \(x = 3\) :
The limit is 6. The learner should know why \(h\) stays nonzero during simplification and why the final value is a tangent slope.
The manual must also teach two transfer examples:
- If \(s(t)\) is position in meters, then \(s'(t)\) is instantaneous velocity in meters per second. Average velocity over shorter intervals approaches instantaneous velocity.
- A corner such as \(f(x) = |x|\) at 0 is not differentiable because the left and right slopes disagree. The issue is not algebraic inconvenience; the tangent slope is not unique.
Classic trap: substituting \(h = 0\) immediately and getting \(\frac{0}{0}\) .
Derivative Rules With Meaning
Derivative rules compress structure. The product rule has two contribution terms:
The chain rule tracks layered change:
The learner should identify inside and outside layers before differentiating. Units should remain visible: a derivative has output units per input unit.
Classic traps:
- differentiating a product by multiplying derivatives
- applying only the outside derivative in a chain-rule problem
- losing units after symbolic work
Base Function Rules
The learner must know the base function rules that derivative and integral procedures call on:
Trig derivatives assume radian measure. Indefinite integrals need \(+ C\) . The learner should check an antiderivative by differentiating it. For example, \(\frac{d}{dx}[-\cos x + C] = \sin x\) , so \(\int \sin x dx = -\cos x + C\) .
Classic traps:
- forgetting the negative sign in \(\int \sin x dx = -\cos x + C\)
- omitting \(+ C\)
- differentiating \(\sin(x^{2})\) without the chain-rule factor \(2x\)
- using degree-mode intuition when a derivative rule assumes radians
Linearization And Optimization
Linearization uses a tangent line as a local model:
It is useful near \(a\) and less trustworthy farther away. Optimization on a closed interval needs a candidate table: endpoints plus critical points. Solving \(f'(x) = 0\) is not the whole task.
Classic traps:
- treating a tangent approximation as exact everywhere
- forgetting endpoints
- assuming every critical point is the requested maximum or minimum
Accumulation And The Fundamental Theorem
A Riemann sum adds many small pieces. If \(r(t)\) is liters per minute, one rectangle has units:
A definite integral is signed accumulation. Velocity above the axis contributes positive displacement; velocity below the axis contributes negative displacement. Total distance uses magnitudes.
The Fundamental Theorem has two directions:
For a variable upper limit such as \(\int_1^{x^{2}} \sin(t) dt\) , the chain rule adds \(2x\) .
Classic traps:
- treating \(dt\) as decorative
- making every area positive when the question asks net change
- forgetting the chain-rule factor in an FTC variable-limit problem
Method Choice
The final habit is to choose the tool from the job:
| Job | Tool |
|---|---|
| nearby behavior | limit |
| instantaneous rate or tangent slope | derivative |
| accumulated total over interval | definite integral |
| endpoint subtraction from a rate | antiderivative / FTC |
| best or worst value | optimization |
| local estimate | linearization |
The representation does not decide the method by itself. A velocity graph can ask for a value, a derivative, an integral, total distance, or a tangent estimate.
Expanded Study Manual Layer
This layer is the richer self-study body behind the compact knowledge-point manual. The compact layer names the course arc and the minimum teachable payload. This expanded layer gives the learner more of what a serious printed course would provide: prerequisite refreshers, theorem conditions, extra worked examples, wrong-solution comparisons, cumulative exercises, and explicit review routes.
Chapter 1 Expanded: Functions, Units, Limits, And Continuity
Prerequisite refresh. A function has input values, output values, a domain where inputs are allowed, and a rule or representation that connects them. The same function can appear as a formula, graph, table, word description, or physical story. Before doing calculus, the learner should always name:
- the input variable and its unit
- the output variable and its unit
- the interval or input value being discussed
- whether the question asks for exact value, nearby behavior, change over an interval, or change at an instant
Representation translation model. Suppose the height of water in a tank is \(h(t)\) centimeters after \(t\) minutes.
| Representation | What to read | Example |
|---|---|---|
| Formula | substitute, simplify, compare | \(h(t)=2t+5\) gives \(h(3)=11\) |
| Table | compare rows and intervals | from \(t=2\) to \(t=6\) , output change is \(h(6)-h(2)\) |
| Graph | read value, trend, slope, and area depending on task | a steep graph means fast change, not necessarily high value |
| Story | identify quantities before formulas | water height per minute means output unit/input unit |
Average rate as the bridge into calculus. Average rate is not a formula to memorize in isolation. It is the slope of a secant line, the quotient of output change by input change, and the first approximation to instantaneous rate:
If \(P(t)\) is profit in dollars after \(t\) months, then \(\frac{P(12)-P(3)}{9}\) is dollars per month. If \(T(d)\) is temperature in degrees after distance \(d\) miles inland, then \(\frac{T(10)-T(0)}{10}\) is degrees per mile.
Worked model, table rate.
| \(t\) minutes | 0 | 2 | 5 | 9 |
|---|---|---|---|---|
| \(V(t)\) liters | 12 | 19 | 31 | 40 |
From \(t=2\) to \(t=9\) , average rate is:
Interpretation: the volume increased at an average rate of 3 liters per minute over that interval. It does not say the rate was exactly 3 at every minute.
Limit language in four surfaces.
- Formula surface: \(\lim_{x\to 2} \frac{x^{2}-4}{x-2}\) . Direct substitution gives \(\frac{0}{0}\) , which is a signal to simplify: \(\frac{x^{2}-4}{x-2}=(x+2)\) for \(x \ne 2\) , so the limit is 4.
- Graph surface: a hole at \((2,4)\) means nearby values may approach 4 even if \(f(2)\) is missing or different.
- Table surface: values from the left and right approach the same number.
- Story surface: a speedometer reading near a time can approach a value even if the sensor dropped the exact reading at that instant.
One-sided limits. The two-sided limit exists only when left and right approaches agree:
If the left limit is 3 and the right limit is 7, the two-sided limit does not exist. The function may still have a value at \(a\) , but the nearby behavior is split.
Continuity decision tree. At \(x=a\) , ask:
- Is \(f(a)\) defined?
- Does \(\lim_{x\to a} f(x)\) exist?
- Are they equal?
All three must pass. A removable hole usually fails condition 1 or 3. A jump fails condition 2. An infinite blow-up fails condition 2 as a finite limit.
Worked continuity comparison.
For \(x \ne 1\) , \(f(x)=x+1\) , so \(\lim_{x\to 1} f(x)=2\) . The value is \(f(1)=5\) . The function is not continuous at 1 because the value and limit disagree. Repair would be redefining \(f(1)=2\) .
Counterexample bank.
- Limit exists but value is different: hole plus filled dot elsewhere.
- Value exists but limit does not: jump with a filled dot at the jump input.
- Left and right limits exist but disagree: piecewise function with different sides.
- Function is continuous but not differentiable: \(|x|\) at 0 has no derivative despite being continuous.
Chapter 1 practice bank.
- Compute average rate for \(s(t)=t^{2}+1\) from \(t=1\) to \(t=4\) and state units if \(s\) is meters.
- A cost table gives \(C(10)=140\) dollars and \(C(25)=260\) dollars. Interpret \(\frac{C(25)-C(10)}{15}\) .
- Simplify \(\lim_{x\to 3} \frac{x^{2}-9}{x-3}\) .
- Describe a graph where \(\lim_{x\to 4} f(x)=10\) but \(f(4)=2\) .
- Give a piecewise example where the left and right limits at 0 disagree.
- Explain why continuity is about matching value and approach, not about “drawing without lifting your pencil” alone.
Chapter 2 Expanded: Derivatives, Rules, And Higher Derivatives
Derivative as a function. The derivative at one input, \(f'(a)\) , is a number: the instantaneous rate or tangent slope at \(a\) . The derivative function, \(f'(x)\) , gives that rate for each input where the derivative exists. The learner should distinguish:
- \(f(a)\) : output value
- \(f'(a)\) : instantaneous rate at \(a\)
- \(f'(x)\) : rate function
- \(f''(x)\) : rate of the rate, often acceleration or concavity
Notation comparison.
| Notation | Meaning |
|---|---|
| \(f'(x)\) | derivative of function \(f\) |
| \(\frac{dy}{dx}\) | derivative of output \(y\) with respect to input \(x\) |
| \(\frac{d}{dx} [expression]\) | command to differentiate the expression |
| \(\Delta y / \Delta x\) | average rate over an interval |
| \(dy\) and \(dx\) | small related changes in differential notation |
Differentiability implies continuity. If a function is differentiable at \(a\) , it is continuous at \(a\) . The converse is false: \(|x|\) is continuous at 0 but not differentiable there because the left and right slopes are different. The proof idea is that a finite tangent slope forces nearby values to approach the actual value. But continuity alone does not promise one clear tangent slope.
Power rule derivation. For positive integer powers, the power rule comes from expanding \((x+h)^{n}\) and watching all terms with remaining \(h\) vanish in the limit. For \(x^{3}\) :
Taking \(h \to 0\) gives \(3x^{2}\) .
Structural derivative rules.
Why the product rule has two terms. If both factors can change, the product changes because the first factor changes while the second is held, and because the second factor changes while the first is held. For \(x^{2} \sin x\) , both \(x^{2}\) and \(\sin x\) change:
Quotient rule worked model. Let:
Here \(f=x^{2}+1\) , \(f'=2x\) , \(g=x-3\) , \(g'=1\) . Then:
Condition: \(x \ne 3\) , because the original function is undefined there.
Quotient-rule trap. A learner writes \((\frac{f}{g})' = f'/g'\) . Test it on \(\frac{x^{2}}{x}\) . The function simplifies to \(x\) , so the derivative should be 1. The false shortcut gives \(\frac{2x}{1}=2x\) , which is wrong except at one input. Repair: quotient change has a numerator-change term and a denominator-change correction term.
Chain-rule layer stack. For:
read layers from outside inward:
- outside: square root
- middle: \(1 + \sin(...)\)
- inside trig: \(\sin(x^{2})\)
- deepest: \(x^{2}\)
Differentiate outward-to-inward:
Higher derivatives. If \(s(t)\) is position, then \(s'(t)\) is velocity and \(s''(t)\) is acceleration. If \(f'(x)>0\) , the function is increasing; if \(f''(x)>0\) , the graph is concave up. Concavity describes how the slope changes, not whether the function is above the axis.
Worked higher-derivative model. Let:
Then:
Critical points are \(x=1\) and \(x=3\) . The second derivative gives \(f''(1)=-6\) , so the graph is concave down and has a local maximum at 1; \(f''(3)=6\) , so it has a local minimum at 3.
Chapter 2 practice bank.
- Differentiate \(x^{5} - 4x^{2} + 7\) .
- Differentiate \(e^{x} \cos x\) .
- Differentiate \(\frac{x^{2}+1}{x-3}\) and state the forbidden input.
- Differentiate \(\sin(3x^{2}-1)\) .
- Find first and second derivatives of \(x^{4} - 2x^{2}\) .
- Explain why differentiability at \(a\) is stronger than continuity at \(a\) .
- Repair the false answer \(\frac{d}{dx}[(x^{2}+1)^{5}] = 5(x^{2}+1)^{4}\) .
- Teach back the product rule using “two changing factors.”
Chapter 3 Expanded: Linearization, MVT, Shape, Related Rates, And Optimization
Linearization procedure.
- Choose a base point \(a\) where \(f(a)\) and \(f'(a)\) are easy.
- Write \(L(x)=f(a)+f'(a)(x-a)\) .
- Use it only near \(a\) .
- State the approximation, not an exact equality.
Worked model, cube root. Estimate \(\sqrt[3]{65}\) using \(f(x)=x^{\frac{1}{3}}\) near \(a=64\) .
The estimate is reasonable because 65 is close to 64.
Mean Value Theorem. If \(f\) is continuous on \([a,b]\) and differentiable on \((a,b)\) , then there is at least one \(c\) in \((a,b)\) such that:
The theorem says some instantaneous rate equals the average rate. It is an existence guarantee, not a recipe that names \(c\) automatically.
MVT worked model. A car travels 120 miles in 2 hours. If its position is continuous over the two hours and differentiable during the trip, then at some moment the speed was exactly 60 miles per hour. The theorem does not say the speed was always 60.
MVT algebra model. Let \(f(x)=x^{2}\) on \([1,3]\) .
The point \(c=2\) lies inside \((1,3)\) , as required.
Shape from derivative signs. A sign chart for \(f'\) tells increasing/decreasing behavior. A sign chart for \(f''\) tells concavity. The learner should not guess graph shape from one value. Use intervals.
Optimization procedure.
- Identify the quantity to maximize or minimize.
- Write it as a function of one variable.
- State the domain or interval.
- Differentiate.
- Find critical points where derivative is zero or undefined.
- Evaluate endpoints if the interval is closed.
- Compare values and interpret.
Worked optimization model. A rectangle has perimeter 20. Maximize its area. Let width be \(x\) ; length is \(10-x\) because \(2x+2L=20\) .
Set \(A'(x)=0\) , so \(x=5\) . The interval is \(0 \le x \le 10\) ; endpoints have area 0; \(x=5\) gives area 25. The square is best.
Related rates setup. Related rates problems ask how one changing quantity affects another. The procedure is:
- Draw or name the relation between quantities.
- Differentiate both sides with respect to time.
- Substitute known values after differentiating.
- Solve for the requested rate.
Worked related-rates model. A circle radius grows at \(\frac{dr}{dt}=2\) cm/s. How fast is area growing when \(r=5\) ?
The area grows at \(20pi\) square centimeters per second.
Chapter 3 practice bank.
- Linearize \(\sqrt{x}\) at \(x=9\) and estimate \(\sqrt{9.2}\) .
- Use MVT on \(f(x)=x^{2}+1\) over \([0,2]\) .
- Give an example where the MVT conditions fail because of a discontinuity.
- Use derivative sign to find increasing intervals for \(x^{3}-3x\) .
- Use second derivative to classify the critical points of \(x^{3}-6x^{2}+9x\) .
- Optimize area of a rectangle with fixed perimeter 32.
- A sphere radius grows at 1 cm/s. Write the derivative equation for volume growth.
- Explain the difference between a local maximum and an absolute maximum.
Chapter 4 Expanded: Accumulation, Antiderivatives, Substitution, And FTC
Accumulation from units. If the integrand is a rate, multiplying by \(dx\) gives a small amount. Adding those small amounts gives total change. This is the most important intuition:
If \(v(t)\) is meters per second and \(dt\) is seconds, \(v(t) dt\) is meters. If \(r(t)\) is gallons per hour and \(dt\) is hours, \(r(t) dt\) is gallons.
Left, right, and midpoint sums. For an interval split into equal widths:
Left sums use left endpoints, right sums use right endpoints, and midpoint sums use midpoints. If the function is increasing, left sums underestimate positive area and right sums overestimate it. If the function is decreasing, the direction reverses.
Worked Riemann model. Approximate \(\int_0^{4} t^{2} dt\) using two right rectangles.
The exact value is \(\frac{64}{3}\) , so the right sum overestimates because \(t^{2}\) is increasing.
Definite integral properties.
These properties are bookkeeping for signed accumulation.
Antiderivative as a family. An antiderivative of \(f\) is any function \(F\) with \(F'=f\) . If \(F\) is one antiderivative, then \(F+C\) is another. This is why indefinite integrals require \(+ C\) .
Basic substitution as reverse chain rule. If the integrand has an inside function and its derivative nearby, use substitution:
Worked substitution model 1.
Let \(u=x^{2}\) , so \(du=2x dx\) . Then:
Check: derivative of \(\sin(x^{2})\) is \(\cos(x^{2})\cdot 2x\) .
Worked substitution model 2.
Let \(u=3x^{2}+1\) , so \(du=6x dx\) . Change bounds: when \(x=0\) , \(u=1\) ; when \(x=1\) , \(u=4\) .
FTC Part 1 with variable limits. If:
then \(A'(x)=f(x)\) when \(f\) is continuous. If the upper limit is \(g(x)\) , chain rule gives:
If the lower limit moves:
FTC Part 2 with endpoint evaluation. If \(F'=f\) , then:
The order matters: upper endpoint minus lower endpoint.
Chapter 4 practice bank.
- Approximate \(\int_0^{6} r(t) dt\) from a three-row rate table and state units.
- Explain why a negative velocity area contributes negative displacement.
- Compute \(\int_1^{3} 4x dx\) .
- Find \(\int (5x^{4} - \sin x) dx\) .
- Use substitution for \(\int 3x^{2} e^{x^{3}} dx\) .
- Evaluate \(\int_0^{2} x(x^{2}+1)^{3} dx\) by substitution.
- Differentiate \(\int_2^{x^{3}} \sqrt{1+t^{2}} dt\) .
- Differentiate \(\int_x^{5} \cos(t^{2}) dt\) .
- Explain why total distance may require splitting an integral where velocity changes sign.
- Teach back the FTC as “accumulation and rate undo each other, with conditions.”
Chapter 5 Expanded: Method Choice, Mixed Review, And Readiness Boundaries
Job-first diagnosis table.
| Prompt language | Likely object | First action |
|---|---|---|
| “approaches” or “near” | limit | check local behavior, one-sided if needed |
| “continuous” | limit plus value | run three continuity checks |
| “instantaneous rate” or “slope” | derivative | identify function and input |
| “best estimate near” | linearization | choose base point and tangent model |
| “increasing/decreasing” | first derivative sign | build sign chart |
| “concave” or “acceleration” | second derivative | compute \(f''\) |
| “maximum/minimum” | optimization | domain, derivative, candidates, endpoints |
| “total change” | definite integral | set bounds and units |
| “recover original from rate” | antiderivative/FTC | find \(F\) and subtract endpoints |
| “accumulation function rate” | FTC Part 1 | evaluate integrand at moving limit, multiply by limit derivative |
Mixed worked model. A particle has velocity \(v(t)=t^{2}-4t+3\) for \(0 \le t \le 4\) .
- Position change from 0 to 4:
2. Acceleration at \(t=2\) :
3. Total distance requires checking where velocity changes sign:
The velocity changes sign at 1 and 3, so split the interval before taking magnitudes.
Wrong-tool comparison. If the prompt says “How much accumulated water entered from 2 to 6 minutes?” a derivative is the wrong first tool. You need an integral of rate over \([2,6]\) . If the prompt says “At what rate is water entering at exactly 6 minutes?” then a derivative or rate value is appropriate. The same story can ask different jobs.
Readiness rubric. A learner is ready to move on when they can:
- name the object before computing
- state required conditions for the theorem used
- compute cleanly enough for the result to be trusted
- attach units or interpretation
- repair one classic mistake
- solve a changed-surface version without relying on the topic label
- explain the method choice to another learner
Cumulative problem set.
- A graph has a hole at \(x=2\) , a filled dot at a different height, and matching left/right approach. State the limit, value, and continuity status.
- Find the derivative of \((x^{2}+1)\sin(3x)\) .
- Differentiate \(\frac{e^{x}}{1+x^{2}}\) .
- Use linearization to estimate \(\ln(1.05)\) .
- Use MVT to prove that some tangent slope of \(x^{3}\) on \([1,2]\) equals 7.
- Classify intervals of increase/decrease for \(f'(x)=(x-1)(x+2)\) .
- Optimize the area of a rectangle with one side along a wall and 40 meters of fencing for the other three sides.
- Compute \(\int 4x \cos(2x^{2}) dx\) .
- Differentiate \(\int_{x^{2}}^{3} e^{t^{2}} dt\) .
- A velocity function changes sign at \(t=2\) . Explain why displacement and distance require different calculations.
- Write a two-paragraph teach-back explaining the difference among derivative, antiderivative, definite integral, and FTC.
Expanded Worked Example And Exercise Bank
This bank gives the learner additional worked examples and practice beyond the core chapter notes. A teacher can assign these as review, and a self-study learner can use them as a check that the manual has become more than a compact outline.
Worked Set A: Limits And Continuity
A1. Algebraic limit with cancellation.
Problem:
Work:
For \(x \ne 5\) , the expression equals \(x+5\) . The limit is:
Repair note: the expression is undefined at \(x=5\) , but the limit asks nearby behavior.
A2. One-sided disagreement.
Problem:
Find \(\lim_{x\to 0} f(x)\) and \(f(0)\) .
Work: left limit is 1; right limit is 3; two-sided limit does not exist. Since \(x\ge 0\) uses the second rule, \(f(0)=3\) .
Repair note: the value exists, but the two-sided approach disagrees.
A3. Continuity from a parameter.
Problem:
Choose \(k\) to make \(f\) continuous at 2.
Work:
Continuity requires \(f(2)=5\) , so \(k=5\) .
A practice prompts.
- Find \(\lim_{x\to -2} \frac{x^{2}-4}{x+2}\) .
- Build a function where \(f(1)=7\) but \(\lim_{x\to 1}f(x)=4\) .
- Give a function continuous at 0 but not differentiable at 0.
- Explain why \(\frac{0}{0}\) is not automatically “no limit.”
- Teach back the difference between value, left limit, right limit, and two-sided limit.
Worked Set B: Derivatives And Rules
B1. First-principles derivative.
Problem: find \(f'(a)\) for \(f(x)=x^{2}+3x\) .
Work:
Take \(h\to 0\) : \(f'(a)=2a+3\) .
B2. Product and chain together.
Problem:
Work:
Repair note: the derivative of \(\cos(2x)\) needs the inside factor 2.
B3. Quotient rule.
Problem:
Work:
Condition: \(x \ne 0\) . This formula does not decide the removable-limit story at 0; that is a separate limit question.
B4. Higher derivative and interpretation.
Problem: \(s(t)=t^{3}-6t^{2}+9t\) . Find velocity and acceleration.
Work:
At \(t=2\) , acceleration is 0. The velocity has a turning point there.
B practice prompts.
- Differentiate \(x^{4} \sin x\) .
- Differentiate \((1+x^{2})^{7}\) .
- Differentiate \(e^{3x}/(1+x)\) .
- Find first and second derivatives of \(x^{4}-4x^{3}\) .
- Repair this answer: \(\frac{d}{dx} \cos(x^{2}) = -\sin(x^{2})\) .
- Teach back how to choose among product, quotient, and chain rule.
Worked Set C: Applications Of Derivatives
C1. Linearization.
Problem: estimate \(\sqrt{15.8}\) using \(f(x)=\sqrt{x}\) near \(a=16\) .
Work:
C2. MVT guarantee.
Problem: If \(f(x)=x^{2}+x\) on \([1,4]\) , find the \(c\) guaranteed by MVT.
Work:
\(\frac{5}{2}\) lies in \((1,4)\) , so it is valid.
C3. Optimization.
Problem: A farmer has 60 meters of fencing for three sides of a rectangular pen against a wall. Maximize area.
Work: Let width be \(x\) ; two widths plus one length use fencing:
Set \(A'=0\) , so \(x=15\) ; then \(L=30\) . Area is 450.
C4. Related rates.
Problem: A square’s side length grows at 3 cm/s. How fast is area growing when side is 10 cm?
Work:
Area grows at 60 square centimeters per second.
C practice prompts.
- Estimate \(\ln(1.02)\) using linearization at 1.
- Use MVT on \(f(x)=x^{3}\) over \([0,2]\) .
- Find intervals of increase/decrease for \(x^{3}-12x\) .
- Optimize area of a rectangle with perimeter 48.
- A circle radius grows at 0.5 m/s. Find area growth at radius 4.
- Repair an optimization solution that forgot endpoints.
Worked Set D: Integrals, Substitution, And FTC
D1. Basic antiderivative.
Problem:
Work:
Check: derivative of \(2cos x\) is \(-2sin x\) .
D2. Definite integral.
Problem:
Work:
D3. Substitution.
Problem:
Let \(u=x^{2}+5\) ; then \(du=2x dx\) , so \(x dx=\frac{du}{2}\) .
D4. Variable-limit FTC.
Problem:
Work: lower limit moves, so use negative sign:
D practice prompts.
- Compute \(\int (3x^{2} + 4cos x) dx\) .
- Evaluate \(\int_0^{2} (x^{2}+1) dx\) .
- Use substitution for \(\int 5x^{4} \cos(x^{5}) dx\) .
- Differentiate \(\int_1^{\sqrt{x}} e^{t^{2}} dt\) .
- Explain when you must split a velocity integral to find total distance.
- Teach back substitution as reverse chain rule.
Mixed Review Checks
- A function is continuous at \(a\) but has a corner there. Which concepts pass and which fail?
- A prompt asks for “how far from start to finish” from velocity. Is that displacement or distance? What should you check?
- A graph question asks for “slope at \(x=3\) .” Which tool and what representation clue do you need?
- A formula has \((x^{2}+1)^{8}\) . Which derivative rule is structurally necessary?
- A rate is in dollars per hour and input is hours. What unit should the definite integral have?
- A learner computes a correct number but gives no unit or interpretation. What evidence is still missing?
Evaluation
Course progress requires the guided path, evidence checks, repair/review prompts, problem set, worked-solution comparison, proof/counterexample work, review pack, and final method-choice teach-back. Readiness requires less-scaffolded mixed problems with explicit domains and floors.
Misses should trigger a targeted repair: identify the missing gist, show the smaller worked comparison, ask for a fresh attempt, and return later through retrieval.
Final Exam Readiness
This layer prepares the manual for the kinds of questions a serious Calculus I final can ask: concept recognition, algebraic cleanup, theorem conditions, applications, units, and mixed method choice.
Limit And Continuity Exam Sprint
A human exam often hides the concept behind algebraic cleanup. The learner should run this decision tree before using a rule:
- Substitute. If the value is ordinary, record the limit and ask whether continuity also requires the function value to match.
- If the form is \(\frac{0}{0}\) , factor, rationalize, combine fractions, or use a known limit.
- If one-sided behavior differs, the two-sided limit does not exist.
- If the expression grows without bound, name the infinite limit or vertical asymptote.
- If the graph has a hole, jump, or asymptote, classify the discontinuity.
Worked model: \(\lim_{x\to 2} \frac{x^{2}-4}{x-2}\) gives \(\frac{0}{0}\) , so factor to \((x-2)\frac{x+2}{x-2}\) . For \(x \ne 2\) , the expression is \(x+2\) , so the limit is 4. The original function is not defined at 2, so the function is not continuous there unless a separate value is supplied.
Trap repair: “The limit is undefined because the expression has \(\frac{0}{0}\) ” is not enough. \(\frac{0}{0}\) is a signal to simplify or compare one-sided behavior.
Derivative Fluency And Theorem Conditions
The learner should recognize rule structure before differentiating:
- Sum and constant multiple: split only across addition and subtraction.
- Product rule: \((fg)'=f'g+fg'\) , not \(f'g'\) .
- Quotient rule: \((\frac{f}{g})'=(f'g-fg')/g^{2}\) .
- Chain rule: differentiate outside, keep inside, multiply by inside derivative.
- Implicit differentiation: differentiate both sides with respect to \(x\) ; every \(y\) term brings \(\frac{dy}{dx}\) .
- Inverse/log/exponential: know \(\frac{d}{dx} e^{x}=e^{x}\) , \(\frac{d}{dx} \ln x=\frac{1}{x}\) , \(\frac{d}{dx} a^{x}=a^{x} \ln a\) , and inverse-function slope as reciprocal slope when applicable.
- Trigonometric rules assume radians.
Theorem condition deck:
- Rolle’s theorem needs continuity on \([a,b]\) , differentiability on \((a,b)\) , and equal endpoint values.
- Mean Value Theorem needs continuity on \([a,b]\) and differentiability on \((a,b)\) .
- Extreme Value Theorem needs continuity on a closed interval.
- First derivative test uses sign changes in \(f'\) .
- Second derivative test uses concavity at a critical point, but inconclusive means use another test.
Practice:
- Differentiate \(x^{2} e^{x}\) , \(\frac{\sin x}{1+x^{2}}\) , \(\ln(1+x^{4})\) , and \(y^{2}+xy=3\) .
- State why MVT cannot be applied to a function with a jump.
- Find intervals of increase and concavity for a polynomial after computing \(f'\) and \(f''\) .
- Repair a solution that finds critical points but forgets endpoints.
Applications Setup Rubric
For related rates:
- Draw or describe the quantities.
- Name what changes with time.
- Write an equation before differentiating.
- Differentiate with respect to time.
- Substitute after differentiating.
- State units and sign.
For optimization:
- Name the objective.
- Name the constraint.
- Reduce to one variable.
- State the domain.
- Find critical points and endpoints.
- Compare values and interpret the winner.
For curve sketching:
- Domain and intercepts.
- First derivative sign chart.
- Critical points and monotonic intervals.
- Second derivative sign chart.
- Concavity and inflection candidates.
- Asymptotes if relevant.
Integration-Technique Bridge
The original change-to-accumulation course teaches definite integral meaning and the FTC. A human final often expects more technique. Add these first-semester techniques as a readiness bridge:
- Substitution: use when the integrand contains a composite function and its derivative. Check by differentiating the answer.
- Integration by parts: use when the integrand is a product and one factor simplifies when differentiated: \(\int u dv = uv - \int v du\) .
- Partial fractions: use for rational functions after factoring the denominator, within the course’s algebra floor.
- Improper integral check: if an endpoint or infinite bound is not ordinary, write a limit before evaluating.
- Average value: \(f_avg = (\frac{1}{b-a}) \int_a^{b} f(x) dx\) .
- Area between curves: integrate top minus bottom after finding intersections.
Worked model: For \(\int x e^{x} dx\) , choose \(u=x\) , \(dv=e^{x} dx\) . Then \(du=dx\) , \(v=e^{x}\) , so the integral is \(x e^{x} - \int e^{x} dx = x e^{x} - e^{x} + C\) .
Trap repair: Do not use integration by parts just because there is a product. If substitution directly matches an inside derivative, substitution may be cleaner.
Limited Differential-Equation Bridge
Some Calculus I finals include separable equations. This course should not pretend to be a full ODE course, but the manual should support the basic pattern:
Practice: solve \(\frac{dy}{dx}=3y\) , \(y(0)=2\) , then explain what the constant means. For a separable non-exponential model, solve \(\frac{dy}{dx}=x y^{2}\) by separating \(y^{-2} dy = x dx\) .
Original Timed Mock Final Blueprint
- Time: 150 minutes.
- Section A: limits, continuity, and theorem conditions.
- Section B: derivative rules, implicit differentiation, MVT/Rolle/EVT, and curve sketching.
- Section C: applications: related rates, optimization, linearization, and units.
- Section D: integration: FTC, substitution, integration by parts, area, average value, and improper-integral setup.
- Section E: cumulative method choice with one separable differential equation if the learner has completed the bridge.
Passing standard: \(75\%\) overall, at least \(60\%\) in each section, and every word problem must include units or a sentence of interpretation.
Practice, Solutions, And Review
The sections below teach, practice, solve, review, and rehearse the course knowledge.
Study Path: Change To Accumulation
This path teaches the first spine of single-variable calculus: how quantities change locally, how small changes accumulate, and how derivatives and integrals connect.
The goal is use-and-teach-back: solve first-course problems and explain why the method fits.
Step 1: Read A Function As Change
A function is not just notation. It is a relationship between an input and an output.
If \(V(t)\) is water volume in liters after \(t\) minutes, then \(t\) is the input and \(V(t)\) is the output. If \(V(2) = 18\) and \(V(7) = 43\) , the input changed by 5 minutes and the output changed by 25 liters. The average rate is:
The units are part of the answer. Saying only 5 loses the meaning.
Classic trap: treating \(f(x)\) as a symbol to manipulate before naming the input, output, interval, and units.
Teach-back: explain why dollars per package and liters per minute are not decoration; they tell what kind of change the number measures.
Step 2: Limits Ask About Nearby Behavior
A limit asks what the function approaches near an input. It does not necessarily ask what happens at the input.
If a graph approaches \(y = 5\) from both sides of \(x = 3\) , but the filled dot is at \((3, 9)\) , then:
Those can differ. The limit reads the nearby path, not the filled dot.
Classic trap: plugging in the point and stopping. Direct substitution is useful when it works, but a hole, jump, or \(\frac{0}{0}\) form needs a closer look.
Teach-back: draw a hole and a filled dot, then ask another learner to answer the limit and the function value separately.
Step 3: Continuity Means The Checks Agree
A function is continuous at \(x = a\) when all three statements are true:
- \(f(a)\) is defined.
- \(\lim_{x \to a} f(x)\) exists.
- \(\lim_{x \to a} f(x) = f(a)\) .
If the limit exists but does not equal the function value, the point is not continuous. If redefining the point fixes the issue, it is a removable discontinuity. If left and right limits disagree, it is a jump. If the values grow without bound, it may be an infinite discontinuity.
Classic trap: saying a function is continuous just because the limit exists. Continuity requires agreement with the actual value.
Teach-back: use the three boxes: defined value, existing limit, equality.
Step 4: Derivative From First Principles
The derivative is the limit of average rates as the interval shrinks to one point.
For \(f(x) = x^{2}\) at \(x = 3\) :
As \(h \to 0\) , the derivative is 6. You do not plug in \(h = 0\) before simplifying. While forming the quotient, \(h\) represents a small nonzero interval.
Classic trap: getting \(\frac{0}{0}\) and stopping. \(\frac{0}{0}\) usually says the quotient still needs simplification before the limit.
Teach-back: explain the derivative as a secant slope becoming a tangent slope.
Step 5: Derivative Rules Are Compressed Structure
Derivative rules save time, but they do not remove meaning.
For \(H(x) = x^{2} \sin x\) , the product rule gives:
The wrong shortcut \(2x \cos x\) differentiates both factors and multiplies the results. That is not the product rule. The product rule has two contribution terms: first factor changes while the second stays, plus second factor changes while the first stays.
Classic trap: applying a rule based on visual habit instead of structure.
Teach-back: explain why a product has two derivative contributions.
Step 6: Chain Rule Tracks Layers And Units
The chain rule handles nested change:
For \((3x^{2} + 1)^{5}\) , the inside is \(3x^{2} + 1\) and the outside is \(u^{5}\) .
The extra \(6x\) is the rate at which the inside changes.
Classic trap: differentiating only the outside layer and forgetting the inside rate.
Teach-back: use the phrase outside rate times inside rate.
Step 7: Linearization Is A Local Model
A derivative gives the slope of the tangent line. Near the base point, the tangent line can estimate the function.
The linearization at \(x = a\) is:
To estimate \(\sqrt{4.1}\) , use \(f(x) = \sqrt{x}\) at \(a = 4\) . Then \(f(4) = 2\) and \(f'(4) = \frac{1}{4}\) .
Classic trap: treating a local approximation as exact or reliable far away.
Teach-back: explain why the tangent line is useful near the base point and less trustworthy farther away.
Step 8: Optimization Needs Candidates And Comparison
Optimization is not just solving \(f'(x) = 0\) . On a closed interval, compare endpoints and critical points.
For \(f(x) = x^{3} - 3x\) on \([-2, 2]\) :
The final answer comes from the candidate table, not from the derivative equation alone.
Classic trap: ignoring endpoints or assuming every critical point is the requested maximum or minimum.
Teach-back: say the checklist: domain, derivative, candidates, compare, justify.
Step 9: Riemann Sums Build Accumulation
A definite integral adds many small pieces.
If \(r(t)\) is a flow rate in liters per minute, then one rectangle contributes:
The units are:
The definite integral \(\int_0^{10} r(t) dt\) is the limit of those rectangle sums as the widths shrink. It measures total liters accumulated over the interval.
Classic trap: treating \(dt\) as decorative. It carries the width and the input units.
Teach-back: point to a rectangle and name its width, height, and units.
Step 10: Definite Integrals Are Signed
A definite integral is signed accumulation. If a graph is below the axis, that part contributes negatively.
If a velocity graph has area 3 above the axis and area 5 below the axis:
The same picture can answer two different questions. Net change keeps signs. Total area or total distance uses magnitudes.
Classic trap: turning every integral area positive even when the question asks for net change.
Teach-back: explain why below-axis velocity means motion in the negative direction, not impossible distance.
Step 11: The Fundamental Theorem Connects Rate And Total
The Fundamental Theorem of Calculus has two practical directions.
If \(A(x) = \int_a^{x} f(t) dt\) , then:
Accumulating a rate and then differentiating returns the current rate.
If \(F'(x) = f(x)\) , then:
This evaluates accumulated change by endpoint subtraction.
Classic trap: forgetting the chain rule for a variable upper limit. If \(A(x) = \int_1^{x^{2}} \sin(t) dt\) , then:
Teach-back: explain FTC as the bridge between local rate and accumulated total.
Step 12: Choose The Tool From The Job
Calculus fluency means choosing the method before calculating.
Use this decision table:
| Job | Tool |
|---|---|
| Nearby behavior | Limit |
| Instantaneous rate or tangent slope | Derivative |
| Local estimate | Linearization |
| Best or worst value | Optimization checklist |
| Accumulated total over an interval | Definite integral |
| Efficient definite integral evaluation | FTC with antiderivative |
Final teach-back: given a velocity graph, explain which questions ask for value, derivative, integral, signed accumulation, or optimization. The representation does not decide the method by itself. The question does.
After The Whiteboard Path
Use the problem set first for less-scaffolded practice, then use the review pack after a delay. The review pack asks you to retrieve before rereading; that is intentional. If you miss a prompt, repair the exact wrong model and try the changed surface before moving on.
Use the proof and counterexample pack when a statement sounds plausible but needs conditions. Calculus is not only formula selection. You should be able to say why a limit does not force continuity, why a product rule shortcut fails, why endpoints matter, and why FTC needs the right direction and conditions.
Use the readiness pack only after the review and proof work. It is stricter than the guided path and checks each major skill area. Passing it is a sign that you are ready for harder follow-up calculus work.
Problem Set
Independent practice is included so the manual owns both teaching and doing.
Problem Set Questions
Each problem names the gist it tests. Work before reading the solution packet.
A. Functions, Limits, And Continuity
- Average Rate And Units
A storage tank has volume \(V(t)\) in liters after \(t\) hours. If \(V(1) = 12\) and \(V(5) = 44\) , compute the average rate of change on \([1, 5]\) and interpret the units. - Limit Versus Function Value
A graph approaches \(y = 6\) from both sides at \(x = 2\) , has an open circle at \((2, 6)\) , and has a filled dot at \((2, -3)\) . State \(\lim_{x \to 2} f(x)\) , state \(f(2)\) , and explain the difference. - Continuity Diagnosis
At \(x = 1\) , a function has \(f(1) = 4\) , left-hand limit 4, and right-hand limit 7. Is it continuous at 1? Which continuity condition fails?
B. Derivatives
- First Principles
Use the limit definition to compute \(f'(2)\) for \(f(x) = x^{2} + x\) . Interpret the result as a tangent slope. - Product Rule Trap
Differentiate \(H(x) = x^{2} \sin x\) and explain why \(2x \cos x\) is not the derivative. - Chain Rule Trap
Differentiate \((5 - 2x^{3})^{4}\) . Identify the inside function and the missing factor many learners forget.
C. Applications
- Linearization
Use linearization at \(x = 9\) to estimate \(\sqrt{9.2}\) . State the base point, tangent-line model, and locality caution. - Closed-Interval Optimization
Find the absolute maximum and minimum of \(f(x) = x^{2} - 4x + 1\) on \([0, 5]\) . Show the candidate table.
D. Integrals And FTC
- Riemann Sum Units
Power \(P(t)\) is measured in kilowatts and time \(t\) in hours. What does \(\int_0^{6} P(t) dt\) measure, and what are its units? - Signed Area
A velocity graph has area 8 above the axis and area 3 below the axis. Give displacement and total distance. - FTC Variable Limit
If \(A(x) = \int_1^{x^{2}} \sin(t) dt\) , find \(A'(x)\) and explain the chain-rule factor.
E. Synthesis
- Method Choice Teach-Back
A graph gives velocity \(v(t)\) . For each question, choose the tool and explain why:
a. Find position change from \(t = 0\) to \(t = 5\) .
b. Decide whether velocity is increasing at \(t = 3\) .
c. Find total distance from \(t = 0\) to \(t = 5\) .
d. Estimate velocity near a time using a tangent line.
Worked Solutions
Solution guidance is included so practice can repair mistakes.
Worked Solutions
1. Average Rate And Units
\(\frac{44 - 12}{5 - 1} = \frac{32}{4} = 8\) . The output is liters and the input is hours, so the average rate is \(8\,\text{liters per hour}\) . It means the tank gained an average of 8 liters each hour over the interval.
2. Limit Versus Function Value
The limit is 6 because the graph approaches \(y = 6\) from both sides as \(x\) approaches 2. The function value is \(f(2) = -3\) because the filled dot gives the actual value. The hole controls nearby behavior; the filled dot controls the value at the point.
3. Continuity Diagnosis
The function is not continuous at 1. Although \(f(1)\) is defined, the two-sided limit does not exist because the left-hand limit is 4 and the right-hand limit is 7. The failed condition is the existence of the two-sided limit.
4. First Principles
For \(f(x) = x^{2} + x\) :
As \(h \to 0\) , the derivative is 5. This is the tangent slope at \(x = 2\) .
5. Product Rule Trap
For \(H(x) = x^{2} \sin x\) :
The expression \(2x \cos x\) is wrong because the derivative of a product is not the product of derivatives. One term holds \(\sin x\) while \(x^{2}\) changes; the other holds \(x^{2}\) while \(\sin x\) changes.
6. Chain Rule Trap
Let the inside be \(u = 5 - 2x^{3}\) . The outside is \(u^{4}\) .
The commonly missed factor is \(-6x^{2}\) , the derivative of the inside.
7. Linearization
Use \(f(x) = \sqrt{x}\) at \(a = 9\) . Then \(f(9) = 3\) and \(f'(x) = \frac{1}{2\sqrt{x}}\) , so \(f'(9) = \frac{1}{6}\) .
This is a local estimate because the tangent line approximates the curve near \(x = 9\) .
8. Closed-Interval Optimization
\(f'(x) = 2x - 4\) , so the critical point is \(x = 2\) .
Candidate values:
The absolute minimum is -3 at \(x = 2\) . The absolute maximum is 6 at \(x = 5\) . Endpoints are required because the interval is closed.
9. Riemann Sum Units
\(P(t)\) has units kilowatts and \(dt\) has units hours. The integral has units kilowatt-hours. It measures total energy used over the first 6 hours.
10. Signed Area
Displacement keeps signs:
Total distance adds magnitudes:
The below-axis region represents motion in the negative direction for displacement, but it still contributes positive distance traveled.
11. FTC Variable Limit
Use FTC Part 1 with the chain rule:
The upper limit is \(x^{2}\) , so the derivative of that upper limit supplies the factor \(2x\) .
12. Method Choice Teach-Back
a. Position change over an interval needs a definite integral: \(\int_0^{5} v(t) dt\)
.
b. Whether velocity is increasing at \(t = 3\)
asks about the derivative of velocity, so use \(v'(3)\)
or the slope of the velocity graph.
c. Total distance needs accumulated magnitude, so split by sign and integrate \(|v(t)|\)
.
d. A nearby estimate from a tangent line uses linearization.
Teach-back summary: choose the tool by the job, not by the fact that the problem contains a graph.
Retrieval Review Pack
Delayed recall and mixed-review prompts are included for exam-like retention.
Review Pack
Use this pack after finishing the guided whiteboard path, then again after a delay. Try each prompt from memory before rereading the lesson. The goal is not speed first. The goal is to recover the right idea, repair the likely wrong move, and explain the method choice.
Review Round 1: Foundations
1. Function, Units, And Average Change
Without looking back, write the average-rate formula in words. Then answer:
\(V(t)\) is volume in liters after \(t\) minutes. If \(V(2) = 15\) and \(V(8) = 51\) , what is the average rate of change on \([2, 8]\) ?
Self-check: \(\frac{51 - 15}{8 - 2} = 6\) liters per minute. A complete answer names the input unit as well as the output unit.
Repair if missed: name input, output, output change, input change, and rate unit before calculating.
2. Limit Versus Value
A graph approaches 4 from both sides at \(x = 1\) , has an open circle at \((1, 4)\) , and a filled dot at \((1, 9)\) .
State the limit, the function value, and one sentence explaining why they differ.
Self-check: \(\lim_{x \to 1} f(x) = 4\) , while \(f(1) = 9\) . The limit uses nearby behavior; the function value uses the filled dot.
Repair if missed: answer two separate questions: “near \(x = 1\) ” and “at \(x = 1\) .”
3. Continuity Three-Box Recall
Write the three continuity conditions at \(x = a\) . Then decide whether this point is continuous:
\(f(a)\) is defined, the left-hand limit is 2, the right-hand limit is 2, and \(f(a) = 5\) .
Self-check: not continuous. The two-sided limit exists and equals 2, but it does not equal the function value.
Repair if missed: continuity needs value, limit, and equality, not only “the graph has a nearby height.”
Review Round 2: Derivatives
4. First-Principles Derivative
Use the limit definition to compute \(f'(1)\) for \(f(x) = x^{2} + 3x\) .
Self-check:
As \(h \to 0\) , the derivative is 5.
Repair if missed: do not set \(h = 0\) while the quotient still has \(h\) in the denominator. Simplify first, then take the limit.
5. Product Rule Contribution Terms
Differentiate \(g(x) = x^{3} \cos x\) . Then explain why the answer has two terms.
Self-check: \(g'(x) = 3x^{2} \cos x - x^{3} \sin x\) . One term changes \(x^{3}\) while holding \(\cos x\) ; the other changes \(\cos x\) while holding \(x^{3}\) .
Repair if missed: say “first changes plus second changes” before writing symbols.
6. Chain Rule Layers
Differentiate \((2x^{2} - 7)^{6}\) . Name the inside, outside, and commonly missed factor.
Self-check: inside \(u = 2x^{2} - 7\) , outside \(u^{6}\) , derivative \(6(2x^{2} - 7)^{5}(4x)\) . The commonly missed factor is \(4x\) .
Repair if missed: circle the inside before applying the outside rule.
Review Round 3: Applications And Accumulation
7. Linearization
Use \(f(x) = \sqrt{x}\) at \(a = 16\) to estimate \(\sqrt{15.6}\) .
Self-check: \(f(16) = 4\) , \(f'(16) = \frac{1}{8}\) , so \(L(x) = 4 + (\frac{1}{8})(x - 16)\) . Then \(L(15.6) = 4 - 0.05 = 3.95\) .
Repair if missed: choose a nearby easy base point, compute value and slope there, then move by \(x - a\) .
8. Optimization Candidate Table
Find the absolute maximum and minimum of \(f(x) = x^{3} - 6x^{2} + 9x\) on \([0, 5]\) .
Self-check: \(f'(x) = 3x^{2} - 12x + 9 = 3(x - 1)(x - 3)\) . Candidates are 0, 1, 3, 5. Values are 0, 4, 0, 20. Minimum is 0 at \(x = 0\) and \(x = 3\) ; maximum is 20 at \(x = 5\) .
Repair if missed: endpoints belong in the table whenever the interval is closed.
9. Integral Units
If \(r(t)\) is measured in meters per second, what does \(\int_0^{12} r(t) dt\) measure, and what are its units?
Self-check: signed displacement over the interval, in meters. The \(dt\) contributes seconds, so meters per second times seconds gives meters.
Repair if missed: multiply the integrand unit by the input unit.
10. Signed Area
A velocity graph has signed regions: 6 above the axis, 4 below, and 3 above. Find displacement and total distance.
Self-check: displacement is \(6 - 4 + 3 = 5\) . Total distance is \(6 + 4 + 3 = 13\) .
Repair if missed: decide whether the question asks for net change or total movement.
Review Round 4: FTC And Method Choice
11. FTC With Variable Upper Limit
If \(A(x) = \int_2^{x^{3}} e^{t} dt\) , find \(A'(x)\) .
Self-check: \(A'(x) = e^{x^{3}} \cdot 3x^{2}\) .
Repair if missed: FTC returns the integrand evaluated at the upper limit, then the chain rule multiplies by the derivative of that upper limit.
12. Mixed Method Choice
For each job, name the tool before calculating:
- Find the slope of a tangent line at one point.
- Decide whether a graph has a removable discontinuity.
- Estimate a function near a base point.
- Find net accumulation over an interval.
- Find absolute maximum and minimum on a closed interval.
Self-check: derivative, continuity checklist, linearization, definite integral, optimization candidate table.
Repair if missed: underline the job phrase in the prompt. The representation does not decide the tool by itself.
Final Teach-Back
Teach the course to another learner in five minutes:
- Limits describe nearby behavior.
- Derivatives describe local rate.
- Integrals add small signed pieces.
- FTC connects rate and total.
- Method choice starts from the job, not from the newest formula.
Use one small example for each sentence. If you cannot supply the example, return to the matching review round before attempting readiness work.
Proof And Counterexample Pack
The proof, condition-checking, and false-rule repair layer is included for serious Calculus I reasoning.
Proof And Counterexample Pack
This pack trains the part of Calculus I that is easy to skip: checking conditions, finding counterexamples to false shortcuts, and explaining why a method is valid. Work each prompt before reading the model resolution.
1. Limit Value Is Not Always Function Value
Prompt: Is the following statement always true?
If \(\lim_{x\to a}f(x)\) exists, then \(f(a)\) equals that limit. Give a counterexample or a proof.
Model resolution: False. Use a removable-hole example:
Then \(\lim_{x \to 2} f(x) = 5\) , but \(f(2) = 9\) . The limit describes nearby behavior; the value at the point can be assigned differently.
Repair target: Do not collapse “near” and “at.” Continuity is the condition that forces them to agree.
2. Continuity Needs Three Conditions
Prompt: Prove or disprove:
If \(f(a)\) is defined and \(\lim_{x\to a}f(x)\) exists, then \(f\) is continuous at \(a\) . Model resolution: False. Let \(f(a) = 10\) , but let the graph approach 3 from both sides near \(a\) . Then \(f(a)\) is defined and the limit exists, but the limit does not equal \(f(a)\) .
Repair target: The missing condition is equality: \(\lim_{x \to a} f(x) = f(a)\) .
3. First-Principles Derivative Requires A Limit
Prompt: Explain why the derivative definition does not allow simply plugging \(h = 0\) into
before simplification.
Model resolution: The quotient describes average rate over a nonzero interval \(h\) . If \(h = 0\) , the denominator is zero, so the quotient is not defined. For many differentiable functions, algebra simplifies the quotient for nonzero \(h\) ; only after that simplification can we ask what the simplified expression approaches as \(h \to 0\) .
Repair target: Treat \(h\) as nonzero during the average-rate stage, then take the limit.
4. Product Rule Counterexample
Prompt: Disprove the false rule
using simple functions.
Model resolution: Let \(f(x) = x\) and \(g(x) = x\) . Then \(fg = x^{2}\) , so \((fg)' = 2x\) . But \(f'g' = 1 \cdot 1 = 1\) . These are not the same function.
Repair target: A changing product needs two contribution terms: \(f'g + fg'\) .
5. Chain Rule Condition Check
Prompt: A learner differentiates \((1 + x^{2})^{5}\) as \(5(1 + x^{2})^{4}\) . Explain the missing reasoning.
Model resolution: The outside function is \(u^{5}\) , but the inside \(u = 1 + x^{2}\) is also changing with respect to \(x\) . The derivative is:
Repair target: A composed function has outside rate times inside rate.
6. Local Linearization Is Not A Global Identity
Prompt: Disprove:
The tangent-line approximation at \(x=a\) gives the exact value of \(f(x)\) for all nearby and faraway \(x\) . Model resolution: Use \(f(x) = x^{2}\) at \(a = 1\) . The tangent line is:
At \(x = 2\) , \(L(2) = 3\) , but \(f(2) = 4\) . The tangent line matches value and slope at the base point, but it is not the whole curve unless the original function is already linear.
Repair target: Linearization is local. The farther the input moves from the base point, the more caution the estimate needs.
7. Closed-Interval Optimization Needs Endpoints
Prompt: Disprove:
An absolute maximum or minimum on a closed interval must occur where \(f'(x)=0\) . Model resolution: Let \(f(x) = x\) on \([0, 1]\) . The derivative is 1, so there is no point where \(f'(x) = 0\) . The absolute minimum is at \(x = 0\) , and the absolute maximum is at \(x = 1\) .
Repair target: Closed-interval optimization compares endpoints and critical points.
8. Definite Integral Is Signed
Prompt: Disprove:
The definite integral always equals geometric area. Model resolution: Let \(f(x) = -1\) on \([0, 2]\) . Then:
The geometric area between the graph and the axis is 2, but the definite integral is signed and equals -2.
Repair target: Ask whether the problem wants signed net change or total area/distance.
9. FTC Needs Continuity Conditions
Prompt: Why do FTC statements include conditions such as continuity of the integrand on the interval?
Model resolution: Conditions tell us when the rate-total bridge is valid. Do not apply FTC as a decoration whenever an integral symbol appears. Identify the accumulation function, interval, and integrand conditions before using endpoint subtraction or differentiating a variable-limit accumulation.
Repair target: State the theorem direction and condition before calculating.
10. Variable Upper Limit Needs Chain Rule
Prompt: Prove by method explanation, not formal epsilon work, why
when the usual FTC and chain-rule conditions hold.
Model resolution: Define \(F(u) = \int_0^{u} f(t) dt\) . By FTC Part 1, \(F'(u) = f(u)\) . The given expression is \(F(g(x))\) . By the chain rule:
Repair target: Name the accumulation function first, then compose it with the moving upper limit.
11. Method-Choice Counterexample
Prompt: A learner says, “If a problem gives a velocity graph, every answer must use an integral.” Give a counterexample.
Model resolution: A velocity graph can ask for many jobs. If the question asks whether velocity is increasing at \(t = 3\) , the tool is the slope of the velocity graph, meaning a derivative of velocity. If the question asks for displacement over an interval, the tool is a definite integral.
Repair target: Choose from the job phrase, not from the representation alone.
12. Teach-Back Proof
Prompt: Teach another learner why the Fundamental Theorem is a bridge between local and accumulated change. Use one sentence for each direction.
Model resolution: Direction one: if you build an accumulated-total function by adding rate from a fixed start to \(x\) , then its derivative gives the current rate. Direction two: if you already know an antiderivative of the rate, the accumulated change over \([a, b]\) is endpoint subtraction \(F(b) - F(a)\) .
Repair target: Keep “differentiate an accumulation” separate from “evaluate an accumulation.”
Course-Owned Readiness Pack
Readiness means mixed, less-scaffolded practice within the course boundary, not AP, placement, credit, or institution-equivalence certification.
Readiness Pack
This readiness check is stricter than the guided lessons. Passing it means you can handle harder tasks across the course spine and can explain your choices. It does not predict AP scores, award college credit, support placement, or claim equivalence with any institution’s course.
Conditions
- Work without the whiteboard path open.
- Use a calculator only for arithmetic checks, not for choosing methods or replacing written reasoning.
- Write enough work that another learner could follow the method.
- After finishing, compare with the scoring guide before rereading the lessons.
Domains And Floors
| Domain | Weight | Floor |
|---|---|---|
| Limits and continuity | 20% | At least 2 of 3 anchors correct |
| Derivatives and rules | 25% | At least 3 of 4 anchors correct |
| Applications and local models | 20% | At least 2 of 3 anchors correct |
| Accumulation and FTC | 25% | At least 3 of 4 anchors correct |
| Method-choice teach-back | 10% | Clear explanation with no major tool mismatch |
Readiness needs both a total score of at least 75% and every domain floor. A high total score with a failed domain floor is “review needed,” not readiness.
Anchor Problems
A. Limits And Continuity
-
A graph approaches 7 from the left and 7 from the right at \(x = 2\) , but the filled dot is at \((2, 1)\) . State the limit, state the function value, and decide continuity.
-
At \(x = 4\) , the left-hand limit is 3, the right-hand limit is 5, and \(f(4) = 3\) . Which continuity condition fails?
-
Give a one-sentence counterexample to the claim: “If a limit exists, the function must be continuous.”
B. Derivatives And Rules
-
Use first principles to compute \(f'(3)\) for \(f(x) = x^{2} - 2x\) .
-
Differentiate \(p(x) = x^{2} e^{x}\) and explain the two contribution terms.
-
Differentiate \((4 - x^{3})^{5}\) and name the inside-rate factor.
-
A position function is in meters and time is in seconds. What are the units of the first derivative? What does the derivative mean?
C. Applications And Local Models
-
Use linearization of \(\sqrt{x}\) at \(a = 25\) to estimate \(\sqrt{24.5}\) . State why the estimate is local.
-
Find absolute maximum and minimum of \(f(x) = x^{3} - 3x + 2\) on \([-2, 2]\) . Show a candidate table.
-
A learner finds \(f'(x) = 0\) at one point and immediately declares an absolute maximum. Name two missing checks.
D. Accumulation And FTC
-
If \(v(t)\) is velocity in meters per second, what does \(\int_1^{6} v(t) dt\) measure, and what are the units?
-
A velocity graph has area 9 above the axis, 4 below, and 2 above. Find displacement and total distance.
-
If \(A(x) = \int_0^{x^{2} + 1} \cos(t) dt\) , find \(A'(x)\) .
-
If \(F'(x) = f(x)\) , explain why \(\int_a^{b} f(x) dx = F(b) - F(a)\) answers accumulated change.
E. Method-Choice Teach-Back
-
A graph gives a changing quantity \(q(t)\) . For each job, choose the tool and write one reason:
- nearby behavior as \(t\) approaches 5
- instantaneous rate at \(t = 5\)
- best value on a closed interval
- accumulated signed change from \(t = 0\) to \(t = 8\)
- efficient evaluation of an integral when an antiderivative is known
Scoring Guide
Limits And Continuity
- Limit 7, value 1, not continuous because the limit does not equal the value.
- The two-sided limit fails to exist because one-sided limits disagree.
- Any removable-discontinuity example is acceptable, such as a function that approaches 2 near \(a\) but is defined as 9 at \(a\) .
Derivatives And Rules
- For \(f(x) = x^{2} - 2x\) :
As \(h \to 0\) , \(f'(3) = 4\) .
- \(p'(x) = 2x e^{x} + x^{2} e^{x}\) . One term changes \(x^{2}\) ; the other changes \(e^{x}\) .
- \(\frac{d}{dx} (4 - x^{3})^{5} = 5(4 - x^{3})^{4}(-3x^{2})\) . The inside-rate factor is \(-3x^{2}\) .
- Meters per second. It is instantaneous velocity, the local rate of position change.
Applications And Local Models
- \(f(25) = 5\) , \(f'(25) = \frac{1}{10}\) , so \(L(24.5) = 5 + (\frac{1}{10})(-0.5) = 4.95\) . It is local because a tangent line models the curve near the base point.
- \(f'(x) = 3x^{2} - 3\) , so critical points are \(x = -1\) and \(x = 1\) . Candidate values: \(f(-2) = -4\) , \(f(-1) = 4\) , \(f(1) = 0\) , \(f(2) = 4\) . Minimum is -4 at \(x = -2\) ; maximum is 4 at \(x = -1\) and \(x = 2\) .
- Missing checks include endpoints, whether the point is in the domain, other critical points, a candidate table, and whether the problem asks absolute or local behavior.
Accumulation And FTC
- Signed displacement from \(t = 1\) to \(t = 6\) , in meters.
- Displacement is \(9 - 4 + 2 = 7\) ; total distance is \(9 + 4 + 2 = 15\) .
- \(A'(x) = \cos(x^{2} + 1) \cdot 2x\) .
- An antiderivative \(F\) tracks accumulated change because its derivative is the rate \(f\) . Endpoint subtraction gives the net accumulated change over the interval.
Method-Choice Teach-Back
- Nearby behavior uses a limit. Instantaneous rate uses a derivative. Best value on a closed interval uses an optimization candidate table. Accumulated signed change uses a definite integral. Efficient integral evaluation uses FTC with an antiderivative.
Readiness Bands
- Ready for harder follow-up calculus: total score at least 75%, every domain floor met, and the method-choice teach-back has no major mismatch.
- Review before next wave: total score at least 60% or one domain floor missed. Return to the review pack and the matching worked examples.
- Guided repair needed: total score below 60% or two or more domain floors missed. Re-enter the whiteboard path at the first weak domain and redo the evidence checks.
What This Check Means
This pack is deliberately stricter than the guided path. Use it to decide whether to move into harder follow-up calculus work or return to review.
Final Exam Rehearsal System
This layer turns the calculus manual from “exam prepared” into a final-ready self-study system within the stated Calculus I scope. The learner should read the manual, work the examples, complete the problem and solution packs, and then use this rehearsal system under exam conditions. The point is not to memorize the manual; it is to prove that the learner can recognize method families, execute calculations cleanly, state theorem hypotheses, and repair common final-exam traps without tutor rescue.
Final-Ready Gate
A learner is final ready for this course’s own serious undergraduate-style final only after all five checks pass.
- Diagnostic Final A: Complete the closed-note diagnostic final in 150 minutes. Use only blank paper, a basic calculator only if the intended external course permits one, and no manual search.
- Domain Floors: Score at least \(80\%\) overall, at least \(70\%\) in every domain, and zero fatal theorem-condition misses. A fatal miss includes applying IVT, EVT, MVT, or FTC without checking the hypotheses that make the theorem legal.
- 72-hour repair loop: For every missed domain, redo the linked manual chapter, write one “why I missed it” sentence, solve two same-family repairs, and solve one transfer variant.
- Validation Final B: Complete a fresh closed-note validation final in 150 minutes after the repair loop. The validation final must use new numbers, new functions, and at least two mixed-method questions.
- Ready-to-sit explanation: In one page, explain which problem families are now automatic, which remain slow, and what the first move is for limits, derivatives, applications, integrals, and FTC problems.
Domain Floors
| Domain | Final-ready evidence | Minimum floor |
|---|---|---|
| Limits and continuity | Computes one-sided limits, classifies discontinuities, and names IVT conditions before using IVT. | \(70\%\) , no theorem used without hypotheses. |
| Derivatives and rules | Differentiates power, trig, exponential, logarithmic, product, quotient, chain, and implicit forms. | \(70\%\) , no rule-family gaps. |
| Theorem applications | Uses MVT/EVT, related rates, optimization, and linearization with setup sentences. | \(70\%\) , no application solved before variables are defined. |
| Accumulation and FTC | Connects signed area, total distance, average value, derivative of an integral, and definite integrals. | \(70\%\) , no FTC part mixed up. |
| Integration methods | Chooses substitution or integration by parts and checks the result by differentiating. | \(70\%\) , including one integration-by-parts integral. |
| Modeling bridge | Solves a separable differential equation or exponential growth/decay prompt and interprets constants. | \(70\%\) , with units or context. |
Diagnostic Final A Blueprint
Use this blueprint after the learner has completed the manual once.
- Part 1, limits and continuity: three limit computations, one removable/jump/infinite discontinuity classification, and one IVT existence argument.
- Part 2, derivative fluency: six derivatives: one product, one quotient, one chain rule, one implicit relation, one logarithmic derivative, and one trig/exponential mix.
- Part 3, theorem conditions: one MVT prompt, one EVT prompt, and one false theorem-use repair where the learner must name the missing hypothesis.
- Part 4, applications: one related-rates problem and one optimization problem; both require variable definitions, equation setup, derivative equation, critical-point check, and final interpretation.
- Part 5, integrals and FTC: one substitution integral, one integration-by-parts integral, one signed-area problem, and one derivative-of-an-integral problem.
- Part 6, synthesis: four short prompts asking whether the first move is algebraic simplification, derivative, definite integral, theorem check, or differential-equation setup.
72-hour Repair Loop
Do not retake the final immediately after a weak diagnostic. Repair should be specific and written down.
- If limits fail: redo the limits chapter, then write the first three moves for algebraic, one-sided, and infinite-limit questions.
- If derivative rules fail: rebuild the derivative rule sheet from memory, then differentiate 12 mixed expressions before checking answers.
- If theorem conditions fail: make a two-column table: theorem name on the left, required hypotheses on the right. Rewrite every failed theorem problem with the hypothesis check as the first line.
- If applications fail: solve two setup-only problems before doing any calculus. A final-ready learner can identify variables and constraints without rushing to a derivative.
- If integrals fail: sort 10 integrals by method before computing any of them. Then compute one substitution, one integration-by-parts integral, one definite area, and one FTC derivative.
- If interpretation fails: attach units, sign meaning, or physical meaning to every numerical answer in the repair set.
Validation Final B Blueprint
Validation Final B should feel like the same course but not the same exam. Use new functions and new contexts.
- Replace at least half of Diagnostic Final A’s functions with trig, exponential, logarithmic, or rational variants.
- Include one optimization problem where the constraint must be derived from a sentence rather than given directly.
- Include one accumulation problem where total distance and net change differ.
- Include one theorem prompt where the conclusion is false because a hypothesis is missing.
- Include one separable differential-equation prompt, such as cooling, growth, or a constrained rate model.
Final Sit Checklist
The learner should not sit the course final until every statement below is true.
- I can state IVT, EVT, MVT, and both parts of FTC with their hypotheses.
- I can differentiate a mixed expression without asking which rule applies.
- I can set up related-rates and optimization variables before calculating.
- I can choose substitution versus integration by parts before trying random algebra.
- I can explain the sign and units of a derivative, integral, or rate answer.
- I have passed Diagnostic Final A, repaired misses, and passed Validation Final B under closed-note timing.
Boundary
Passing this Final Exam Rehearsal System means the learner is final ready within this Calculus I scope. Topics outside this path, such as sequences and series, parametric curves, polar coordinates, or multivariable calculus, require separate study.