Calculus I · Unit 3B · practice

Unit 3B Cumulative Practice

Practice method

Work in three passes

First, classify. Name the integral output and structural method before writing algebra. This separates a recognition error from a calculation error.

Second, solve without the key. Record a complete attempt, including bounds, constants, domains, units, or interpretation when the prompt asks for them.

Third, reveal one answer at a time. Compare the first line where your work differs, close the answer, and redo that item from a blank start.

Cumulative Practice

Exercise

Find the area enclosed by y=x2y=x^2 and y=2x+3y=2x+3.

Answer reveal

Exercise 1 answer

Write a real attempt before opening the supplied answer.

Exercise

Rotate that same enclosed region about the horizontal line y=1y=-1. Set up and evaluate the washer integral.

Answer reveal

Exercise 2 answer

Write a real attempt before opening the supplied answer.

Exercise

Rotate that same enclosed region about the vertical line x=2x=-2. Set up and evaluate the shell integral.

Answer reveal

Exercise 3 answer

Write a real attempt before opening the supplied answer.

Exercise

The base is the region enclosed by y=x2y=x^2 and y=2x+3y=2x+3. Cross-sections perpendicular to the xx-axis are squares. Find the volume.

Answer reveal

Exercise 4 answer

Write a real attempt before opening the supplied answer.

Exercise

Find the arc length of y=x3/2y=x^{3/2} on [0,4/9][0,4/9].

Answer reveal

Exercise 5 answer

Write a real attempt before opening the supplied answer.

Exercise

A rod occupies [0,1][0,1] and has density λ(x)=1+x2\lambda(x)=1+x^2. Find its mass and center of mass.

Answer reveal

Exercise 6 answer

Write a real attempt before opening the supplied answer.

Exercise

A spring has constant k=200N/mk=200\,\mathrm{N/m}. Find the work required to stretch it from 0.10m0.10\,\mathrm{m} to 0.30m0.30\,\mathrm{m} beyond equilibrium.

Answer reveal

Exercise 7 answer

Write a real attempt before opening the supplied answer.

Exercise

A 4m4\,\mathrm{m}-long triangular trough has ends 2m2\,\mathrm{m} deep and 3m3\,\mathrm{m} wide at the top. It is full of water. Set up and evaluate the work to pump the water to the top edge using 9800N/m39800\,\mathrm{N/m^3}.

Answer reveal

Exercise 8 answer

Write a real attempt before opening the supplied answer.

Exercise

A triangular vertical gate has a 4m4\,\mathrm{m} top edge at the water surface and a vertex 3m3\,\mathrm{m} below. Find the hydrostatic force using 9800N/m39800\,\mathrm{N/m^3}.

Answer reveal

Exercise 9 answer

Write a real attempt before opening the supplied answer.

Exercise

Marginal cost is C(q)=15+0.02qC'(q)=15+0.02q dollars per unit and fixed cost is C(0)=2000C(0)=2000. Find C(300)C(300).

Answer reveal

Exercise 10 answer

Write a real attempt before opening the supplied answer.

Exercise

A probability density has the form p(x)=kxp(x)=kx on [0,2][0,2]. Find kk, verify normalization, and compute E[X]E[X].

Answer reveal

Exercise 11 answer

Write a real attempt before opening the supplied answer.

After the explanation

Use the section idea

Reading lens

Mixed applications test modeling recognition: commit to a diagram and slice statement before looking for a familiar formula.

Mental model

A complete solution connects context, variable, bounds, slice contribution, integral, computation, units, interpretation, and a reasonableness check.

Decision

Classify the output and geometry first, solve from a blank start, then reveal one worked answer only to diagnose the earliest divergent decision.

Common trap

Reading a key before forming a setup or treating every wrong result as algebra when the real error was a radius, width, density, or bound.

Check yourself

Can you rebuild the setup without the answer open and defend every factor in a sentence?

Source & rights

Original instruction with traceable references.

BetterGrades-original; no direct adaptation declared in the verified handoff.

Reference textbooks remain rights-separated and are not published as application assets. Any direct adaptation requires separate identification and attribution.