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Calculus 2 final exam review

20 practice problems across the topics a Calculus 2 final usually covers, in course order, each with a worked solution checked line by line. Your own exam may differ, so check your syllabus.

Try each problem on paper before opening its solution. If one gives you trouble, the topic link above it has more like it. How we verify

1. Integration by parts

Problem 4.168

medium Video
Find \( \displaystyle \int \left(2 x - 1\right) \cos{\left(4 x - 2 \right)} \, dx \). (Omit the constant of integration.)
  1. \[ \int \left(2 x - 1\right) \cos{\left(4 x - 2 \right)}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \left(2 x \cos{\left(4 x - 2 \right)} - \cos{\left(4 x - 2 \right)}\right)\, dx \]
    linearityDistribute the cosine term.✓ Proved
  3. \[ = 2 \int x \cos{\left(4 x - 2 \right)}\, dx - \int \cos{\left(4 x - 2 \right)}\, dx \]
    linearitySplit the integral into two parts.✓ Proved
  4. \[ = \frac{x \sin{\left(4 x - 2 \right)}}{2} - 2 \int \frac{\sin{\left(4 x - 2 \right)}}{4}\, dx - \int \cos{\left(4 x - 2 \right)}\, dx \]
    parts algebra simplifyApply integration by parts to the first integral, where u = x and dv = cos(4*x - 2)dx. Distribute the 2 into the parentheses. Simplify the coefficient of the first term.✓ Proved
  5. \[ = \frac{x \sin{\left(4 x - 2 \right)}}{2} + \frac{\cos{\left(4 x - 2 \right)}}{8} - \int \cos{\left(4 x - 2 \right)}\, dx \]
    antiderivative algebraIntegrate the sine term. Simplify the sign and fraction.✓ Proved
  6. \[ = \frac{x \sin{\left(4 x - 2 \right)}}{2} - \frac{\sin{\left(4 x - 2 \right)}}{4} + \frac{\cos{\left(4 x - 2 \right)}}{8} \]
    antiderivative simplifyIntegrate the final cosine term. Final simplification of the antiderivative.✓ Proved
Answer \( \frac{x \sin{\left(4 x - 2 \right)}}{2} - \frac{\sin{\left(4 x - 2 \right)}}{4} + \frac{\cos{\left(4 x - 2 \right)}}{8} + C \)
Top: the graph of F = x·sin(4x - 2)/2 - sin(4x - 2)/4 + cos(4x - 2)/8. A tangent line slides along it, and its slope is plotted below as it goes, tracing f = (2x - 1)·cos(4x - 2).
A second solution, written separately

By gpt-oss:20b, without seeing the first. SymPy checked every line.

  1. \[ \int \left(2 x - 1\right) \cos{\left(4 x - 2 \right)}\, dx \]
    integral✓ Proved
  2. \[ = \frac{\int \left(4 x - 2\right) \cos{\left(4 x - 2 \right)}\, dx}{2} \]
    algebraFactor 2*x-1 as (1/2)*(4*x-2)✓ Proved
  3. \[ = \frac{\left(4 x - 2\right) \sin{\left(4 x - 2 \right)}}{8} - \frac{\int \sin{\left(4 x - 2 \right)}\, dx}{2} \]
    partsIntegrate by parts with u=4*x-2, dv=cos(4*x-2)dx✓ Proved
  4. \[ = \frac{\left(4 x - 2\right) \sin{\left(4 x - 2 \right)}}{8} + \frac{\cos{\left(4 x - 2 \right)}}{8} \]
    antiderivative simplifyIntegral of sin(4*x-2) is -cos(4*x-2)/4 Combine constants✓ Proved

✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

2. Trigonometric integrals

Problem 4.362

medium Video
Find \( \displaystyle \int \cos^{2}{\left(3 x - 1 \right)} \, dx \). (Omit the constant of integration.)
  1. \[ \int \cos^{2}{\left(3 x - 1 \right)}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \left(\frac{\cos{\left(6 x - 2 \right)}}{2} + \frac{1}{2}\right)\, dx \]
    trig-identityUse the power-reduction identity cos(u)^2 = (1 + cos(2u))/2.✓ Proved
  3. \[ = \int \frac{1}{2}\, dx + \int \frac{\cos{\left(6 x - 2 \right)}}{2}\, dx \]
    linearity algebraSplit the integral into two parts. Factor out the constant 1/2.✓ Proved
  4. \[ = \frac{x}{2} + \int \frac{\cos{\left(6 x - 2 \right)}}{2}\, dx \]
    antiderivativeIntegrate the first term.✓ Proved
  5. \[ = \frac{x}{2} + \frac{\sin{\left(6 x - 2 \right)}}{12} \]
    antiderivative simplifyIntegrate the second term using the substitution rule for cos(ax+b). Simplify the final expression.✓ Proved
Answer \( \frac{x}{2} + \frac{\sin{\left(6 x - 2 \right)}}{12} + C \)
Top: the graph of F = x/2 + sin(6x - 2)/12. A tangent line slides along it, and its slope is plotted below as it goes, tracing f = cos(3x - 1)².
A second solution, written separately

By gpt-oss:20b, without seeing the first. SymPy checked every line.

  1. \[ \int \cos^{2}{\left(3 x - 1 \right)}\, dx \]
    integral✓ Proved
  2. \[ = \int \left(\frac{\cos{\left(6 x - 2 \right)}}{2} + \frac{1}{2}\right)\, dx \]
    trig-identityUse cos²θ = (1+cos2θ)/2 with θ = 3x-1✓ Proved
  3. \[ = \int \frac{1}{2}\, dx + \int \frac{\cos{\left(6 x - 2 \right)}}{2}\, dx \]
    linearitySplit the integral✓ Proved
  4. \[ = \frac{x}{2} + \int \frac{\cos{\left(6 x - 2 \right)}}{2}\, dx \]
    antiderivative∫1/2 dx = x/2✓ Proved
  5. \[ = \frac{x}{2} + \frac{\int \cos{\left(6 x - 2 \right)}\, dx}{2} \]
    linearityFactor out the constant 1/2✓ Proved
  6. \[ = \frac{x}{2} + \frac{\sin{\left(6 x - 2 \right)}}{12} \]
    antiderivative simplify∫cos(6x-2) dx = sin(6x-2)/6 Combine constants✓ Proved

✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

3. Trigonometric substitution

Evaluate \( \displaystyle \int \frac{1}{x^{2} \sqrt{x^{2} + 9}}\, dx \).
  1. The radical suggests x = 3 tan θ.
    Reviewed
  2. \[ 9 \tan^{2}{\left(\theta \right)} + 9 = 9 \sec^{2}{\left(\theta \right)} \]
    The identity that clears the square root.✓ Proved
  3. Rewrite the integral in θ, integrate, then use a right triangle to express the trig functions of θ in terms of x.
    Reviewed
  4. \[ \frac{d}{d x} \left(- \frac{\sqrt{x^{2} + 9}}{9 x}\right) = \frac{1}{x^{2} \sqrt{x^{2} + 9}} \]
    Differentiating the answer returns the integrand.✓ Proved
Answer \( - \frac{\sqrt{x^{2} + 9}}{9 x} + C \)

✓ Nihil obstat Lines: 2 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

4. Partial fractions

Problem 4.276

medium Video
Find \( \displaystyle \int \frac{2 x - 1}{2 x \left(2 x + 2\right)} \, dx \). (Omit the constant of integration.)
  1. \[ \int \frac{2 x - 1}{2 x \left(2 x + 2\right)}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \frac{2 x - 1}{4 x^{2} + 4 x}\, dx \]
    algebraExpand the denominator.✓ Proved
  3. \[ = \int \left(\frac{2 x}{4 x^{2} + 4 x} - \frac{1}{4 x^{2} + 4 x}\right)\, dx \]
    linearitySplit the integrand into two parts.✓ Proved
  4. \[ = \int \left(- \frac{1}{4 x^{2} + 4 x} + \frac{1}{2 x + 2}\right)\, dx \]
    simplifySimplify the first term by canceling x.✓ Proved
  5. \[ = \int \frac{1}{2 x + 2}\, dx - \int \frac{1}{4 x^{2} + 4 x}\, dx \]
    linearitySplit the integral again.✓ Proved
  6. \[ = - \int \frac{1}{4 x \left(x + 1\right)}\, dx + \int \frac{1}{2 x + 2}\, dx \]
    algebraFactor out the constant from the second denominator.✓ Proved
  7. \[ = \int \frac{1}{2 x + 2}\, dx - \int \frac{1}{4 x^{2} + 4 x}\, dx \]
    algebraFactor out 4 from the second term.✓ Proved
  8. \[ = - \frac{\int \frac{1}{x \left(x + 1\right)}\, dx}{4} + \int \frac{1}{2 x + 2}\, dx \]
    linearityPull out the constant factor.✓ Proved
  9. \[ = \int \frac{1}{2 x + 2}\, dx - \frac{\int \left(- \frac{1}{x + 1} + \frac{1}{x}\right)\, dx}{4} \]
    partial-fractionsApply partial fraction decomposition to the second term.✓ Proved
  10. \[ = - \frac{\int \frac{1}{x}\, dx}{4} + \frac{\int \frac{1}{x + 1}\, dx}{4} + \int \frac{1}{2 x + 2}\, dx \]
    linearityDistribute the constant and split the integral.✓ Proved
  11. \[ = - \frac{\ln{\left(x \right)}}{4} + \frac{\ln{\left(x + 1 \right)}}{4} + \frac{\ln{\left(2 x + 2 \right)}}{2} \]
    antiderivativeEvaluate the integrals using the natural logarithm rule.✓ Proved
Answer \( \frac{- \ln{\left(x \right)} + 3 \ln{\left(x + 1 \right)}}{4} + C \)
Top: the graph of F = -log(x)/4 + 3log(x + 1)/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f = (2x - 1)/(2x·(2x + 2)).
A second solution, written separately

By gpt-oss:20b, without seeing the first. SymPy checked every line.

  1. \[ \int \frac{2 x - 1}{2 x \left(2 x + 2\right)}\, dx \]
    integral✓ Proved
  2. \[ = \int \frac{2 x - 1}{4 x \left(x + 1\right)}\, dx \]
    simplifyCombine constants in the denominator.✓ Proved
  3. \[ = \int \left(\frac{3}{4 x + 4} - \frac{1}{4 x}\right)\, dx \]
    partial-fractionsDecompose into simpler fractions.✓ Proved
  4. \[ = - \frac{\ln{\left(x \right)}}{4} + \frac{3 \ln{\left(x + 1 \right)}}{4} \]
    antiderivativeIntegrate each term.✓ Proved

✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

5. Improper integrals

Evaluate \( \displaystyle \int_{0}^{\infty} e^{- 4 x} \, dx \), or show that it diverges.
  1. The integral is improper at infinity; replace that bound by T and take a limit.
    Reviewed
  2. \[ \frac{d}{d x} \left(- \frac{e^{- 4 x}}{4}\right) = e^{- 4 x} \]
    An antiderivative, checked by differentiating.✓ Proved
  3. \[ 1 \cdot \frac{1}{4} - \frac{e^{- 4 T}}{4} = \frac{1}{4} - \frac{e^{- 4 T}}{4} \]
    The integral with T in place of the bad bound.Reviewed
  4. As T → \infty, this approaches 1/4.
    Reviewed
  5. \[ \lim_{T \to \infty}\left(\frac{1}{4} - \frac{e^{- 4 T}}{4}\right) = \frac{1}{4} \]
    The limit.✓ Proved
Answer \( \frac{1}{4} \)

✓ Nihil obstat Lines: 2 proved, 3 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

6. Volumes by disks and washers

The region between \( \displaystyle y = x \) and \( \displaystyle y = x^{2} \) is revolved about the x-axis. Find the volume.
  1. \[ - x \left(x - 1\right) = - x^{2} + x \]
    The curves meet at x = 0 and x = 1.✓ Proved
  2. Cross sections are washers: outer radius x, inner radius x**2.
    Reviewed
  3. \[ \int\limits_{0}^{1} \pi \left(- x^{4} + x^{2}\right)\, dx = \frac{2 \pi}{15} \]
    V = ∫ A(x) dx.✓ Proved
Answer \( \frac{2 \pi}{15} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

7. Volumes by cylindrical shells

The region under \( \displaystyle y = 4 - x^{2} \) for \( \displaystyle 0 \le x \le 2 \) is revolved about the y-axis. Use shells to find the volume.
  1. A shell at x has radius x, height f(x) and thickness dx, so its volume is 2πx f(x) dx.
    Reviewed
  2. \[ \int\limits_{0}^{2} 2 \pi x \left(4 - x^{2}\right)\, dx = 8 \pi \]
    V = ∫ 2πx f(x) dx.✓ Proved
Answer \( 8 \pi \)

✓ Nihil obstat Lines: 1 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

8. Surface area of revolution

Find the area of the surface obtained by rotating \( \displaystyle y = 2 x \), \( \displaystyle 0 \le x \le 3 \), about the \( \displaystyle x \)-axis.
  1. \[ \frac{d}{d x} 2 x = 2 \]
    y′.✓ Proved
  2. Rotating about the x-axis, the radius is y, so S = ∫ 2π·(radius)·√(1 + (y′)²) dx.
    Reviewed
  3. \[ 4 \sqrt{5} \pi x \]
    Simplify the integrand.Reviewed
  4. \[ \int\limits_{0}^{3} 4 \sqrt{5} \pi x\, dx = 18 \sqrt{5} \pi \]
    Integrate.✓ Proved
Answer \( 18 \sqrt{5} \pi \approx 126.4467 \)

✓ Nihil obstat Lines: 2 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

9. Work: springs, pumping and cables

A force of 30 N holds a spring stretched \( \displaystyle \frac{1}{5} \) m beyond its natural length. How much work does it take to stretch it from \( \displaystyle \frac{2}{5} \) m to \( \displaystyle \frac{1}{2} \) m beyond its natural length?
  1. Hooke's law: F(x) = kx, with x the stretch beyond natural length.
    Reviewed
  2. \[ 150 \]
    k from the given force and stretch (N/m).Reviewed
  3. \[ \int\limits_{\frac{2}{5}}^{\frac{1}{2}} 150 x\, dx = \frac{27}{4} \]
    W = ∫ F(x) dx.✓ Proved
Answer \( \frac{27}{4} \approx 6.75\ \text{J} \)

✓ Nihil obstat Lines: 1 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

10. Centers of mass and centroids

Find the centroid of the region bounded by \( \displaystyle y = 5 - x \) and \( \displaystyle y = 0 \) for \( \displaystyle 0 \le x \le 2 \).
  1. \[ \int\limits_{0}^{2} \left(5 - x\right)\, dx = 8 \]
    The area.✓ Proved
  2. \[ \int\limits_{0}^{2} x \left(5 - x\right)\, dx = \frac{22}{3} \]
    The moment about the y-axis.✓ Proved
  3. \[ \int\limits_{0}^{2} \frac{\left(5 - x\right)^{2}}{2}\, dx = \frac{49}{3} \]
    The moment about the x-axis: ∫ ½(top² − bottom²) dx.✓ Proved
  4. \[ \left[\begin{matrix}\frac{11}{12}\\\frac{49}{24}\end{matrix}\right] \]
    Divide each moment by the area.Reviewed
Answer \( (\bar{x}, \bar{y}) = \left(\frac{11}{12}, \frac{49}{24}\right) \)

✓ Nihil obstat Lines: 3 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

11. Separable differential equations

Problem 6.5

medium Video
Solve the initial-value problem \( \displaystyle \dfrac{dy}{dx} = 2 y,\ y(0) = 4 \).
  1. Separate the variables, putting every y on one side and every x on the other, and integrate both sides.
    Reviewed
  2. Use y(0) to find the constant of integration, then solve for y.
    Reviewed
  3. \[ \frac{d}{d x} 4 e^{2 x} = 8 e^{2 x} \]
    The solution satisfies the equation.✓ Proved
  4. \[ 4 \]
    And the initial condition.Reviewed
Answer \( y = 4 e^{2 x} \)
The slope field of y' = 2y: short segments showing the slope at each point. Several solution curves follow the field; the one through (0, 4) is highlighted, y = 4e^(2x).

✓ Nihil obstat Lines: 1 proved, 3 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

12. First-order linear equations

Problem 6.62

medium Video
Solve \( \displaystyle y' + 2y = e^{- 2 x} \) with \( \displaystyle y(0) = 4 \).
  1. The equation is linear in standard form; the integrating factor is e^(∫2 dx) = e^(2x).
    Reviewed
  2. \[ \frac{d}{d x} Y{\left(x \right)} e^{2 x} = 2 Y{\left(x \right)} e^{2 x} + e^{2 x} \frac{d}{d x} Y{\left(x \right)} \]
    Multiplying by e^(ax) turns the left side into (e^(ax) y)'.✓ Proved
  3. \[ \int 1\, dx = x \]
    Integrate the right side.✓ Proved
  4. Setting x = 0 and y = 4 fixes the constant of integration: C = 4.
    Reviewed
  5. \[ \left(2 x + 8\right) e^{- 2 x} + \frac{d}{d x} \left(x + 4\right) e^{- 2 x} = e^{- 2 x} \]
    The solution satisfies the equation.✓ Proved
  6. \[ 4 \]
    And the initial condition.Reviewed
Answer \( y = \left(x + 4\right) e^{- 2 x} \)
The slope field of y' = -2y + e^(-2x): short segments showing the slope at each point. Several solution curves follow the field; the one through (0, 4) is highlighted, y = (x + 4)·e^(-2x).

✓ Nihil obstat Lines: 3 proved, 3 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

13. Geometric series

Problem 7.2

medium Video
Does \( \displaystyle \sum_{n=0}^{\infty} - \left(- \frac{3}{5}\right)^{n} \) converge? If so, find its sum.
  1. \[ -1 \]
    The first term, a.Reviewed
  2. \[ - \frac{3}{5} \]
    The common ratio, r.Reviewed
  3. |r| = 3/5 < 1, so the series converges to a/(1 − r).
    Reviewed
  4. \[ - \frac{5}{8} \]
    a/(1 − r).Reviewed
Answer \( - \frac{5}{8} \)
Bars show the terms -(-3/5)^n for n = 0 to 23; dots show the running totals. The totals level off at -5/8.

✓ Nihil obstat Lines: 4 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

14. Series convergence tests

Does \( \displaystyle \sum_{n=1}^{\infty} \frac{3^{n}}{n!} \) converge or diverge?
  1. Factorials suggest the ratio test.
    Reviewed
  2. \[ \frac{3^{- n} 3^{n + 1} n!}{\left(n + 1\right)!} = \frac{3}{n + 1} \]
    a_(n+1)/a_n.✓ Proved
  3. \[ \lim_{n \to \infty}\left(\frac{3}{n + 1}\right) = 0 \]
    The limit is 0 < 1, so the series converges.✓ Proved
Answer \( \text{converges} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

15. Comparison and limit comparison tests

Determine whether \( \displaystyle \sum_{n=1}^{\infty} \frac{4 n^{2} + 4 n + 4}{3 n^{4} + 4 n^{3} + 3 n^{2} + 2 n + 1} \) converges or diverges.
  1. For large n the term behaves like 1/n^2, so compare with that p-series.
    Reviewed
  2. \[ \lim_{n \to \infty}\left(\frac{n^{2} \left(4 n^{2} + 4 n + 4\right)}{3 n^{4} + 4 n^{3} + 3 n^{2} + 2 n + 1}\right) = \frac{4}{3} \]
    The limit is finite and positive, so the two series do the same thing.✓ Proved
  3. Σ 1/n^2 converges (p > 1), so the given series converges.
    Reviewed
Answer \( \text{converges} \)

✓ Nihil obstat Lines: 1 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

16. Radius of convergence

Find the radius of convergence of \( \displaystyle \sum_{n=1}^{\infty} \frac{3^{- n} \left(x - 1\right)^{n}}{n} \).
  1. Use the ratio test on the absolute values of the terms.
    Reviewed
  2. \[ \lim_{n \to \infty}\left(\frac{3^{n} 3^{- n - 1} n \left(x - 1\right)^{- n} \left(x - 1\right)^{n + 1}}{\left(n + 1\right) \left(x - 1\right)}\right) = \frac{1}{3} \]
    |a_(n+1)/a_n| → 1/3·|x − 1|.✓ Proved
  3. The series converges when 1/3|x − 1| < 1, that is |x − 1| < 3.
    Reviewed
Answer \( R = 3 \)

✓ Nihil obstat Lines: 1 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

17. Taylor and Maclaurin polynomials

Find the Maclaurin polynomial of degree 5 for \( \displaystyle f(x) = \sqrt{x + 1} \).
  1. p_n(x) = Σ f⁽ᵏ⁾(0)/k! · xᵏ, for k = 0 to n.
    Reviewed
  2. \[ \left. \sqrt{x + 1} \right|_{\substack{ x=0 }} = 1 \]
    f⁽0⁾(0).✓ Proved
  3. \[ \left. \frac{d}{d x} \sqrt{x + 1} \right|_{\substack{ x=0 }} = \frac{1}{2} \]
    f⁽1⁾(0).✓ Proved
  4. \[ \left. \frac{d^{2}}{d x^{2}} \sqrt{x + 1} \right|_{\substack{ x=0 }} = - \frac{1}{4} \]
    f⁽2⁾(0).✓ Proved
  5. \[ \left. \frac{d^{3}}{d x^{3}} \sqrt{x + 1} \right|_{\substack{ x=0 }} = \frac{3}{8} \]
    f⁽3⁾(0).✓ Proved
  6. \[ \left. \frac{d^{4}}{d x^{4}} \sqrt{x + 1} \right|_{\substack{ x=0 }} = - \frac{15}{16} \]
    f⁽4⁾(0).✓ Proved
  7. \[ \left. \frac{d^{5}}{d x^{5}} \sqrt{x + 1} \right|_{\substack{ x=0 }} = \frac{105}{32} \]
    f⁽5⁾(0).✓ Proved
  8. \[ 105 \cdot \frac{1}{32} x^{5} \cdot 1 \cdot \frac{1}{120} - 15 \cdot \frac{1}{16} x^{4} \cdot 1 \cdot \frac{1}{24} + 3 \cdot \frac{1}{8} x^{3} \cdot 1 \cdot \frac{1}{6} - 1 \cdot \frac{1}{4} x^{2} \cdot 1 \cdot \frac{1}{2} + 1 \cdot \frac{1}{2} x 1 + 1 = \frac{7 x^{5}}{256} - \frac{5 x^{4}}{128} + \frac{x^{3}}{16} - \frac{x^{2}}{8} + \frac{x}{2} + 1 \]
    Assemble the polynomial.✓ Proved
Answer \( p_{5}(x) = \frac{7 x^{5}}{256} - \frac{5 x^{4}}{128} + \frac{x^{3}}{16} - \frac{x^{2}}{8} + \frac{x}{2} + 1 \)

✓ Nihil obstat Lines: 7 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

18. Tangent lines to parametric curves

Find the equation of the tangent line to \( \displaystyle x = e^{t},\ y = t^{3} \) at \( \displaystyle t = 1 \).
  1. dy/dx = (dy/dt)/(dx/dt).
    Reviewed
  2. \[ \frac{d}{d t} e^{t} = e^{t} \]
    dx/dt.✓ Proved
  3. \[ \frac{d}{d t} t^{3} = 3 t^{2} \]
    dy/dt.✓ Proved
  4. \[ \frac{3}{e} \]
    The slope at t = 1.Reviewed
  5. \[ \left[\begin{matrix}e\\1\end{matrix}\right] \]
    The point.Reviewed
  6. \[ \frac{3 x - 3 e}{e} + 1 = \frac{3 x}{e} - 2 \]
    Point-slope form.✓ Proved
Answer \( y = \frac{3 x}{e} - 2 \)

✓ Nihil obstat Lines: 3 proved, 3 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

19. Arc length of parametric curves

Find the length of the curve \( \displaystyle x = 3 t - 3 \sin{\left(t \right)} \), \( \displaystyle y = 3 - 3 \cos{\left(t \right)} \), \( \displaystyle 0 \le t \le 2 \pi \).
  1. \[ \left[\begin{matrix}\frac{d}{d t} \left(3 t - 3 \sin{\left(t \right)}\right)\\\frac{d}{d t} \left(3 - 3 \cos{\left(t \right)}\right)\end{matrix}\right] = \left[\begin{matrix}3 - 3 \cos{\left(t \right)}\\3 \sin{\left(t \right)}\end{matrix}\right] \]
    Velocity components.✓ Proved
  2. \[ \left(3 - 3 \cos{\left(t \right)}\right)^{2} + 9 \sin^{2}{\left(t \right)} = 36 \sin^{2}{\left(\frac{t}{2} \right)} \]
    (dx/dt)² + (dy/dt)², simplified with 1 − cos t = 2 sin²(t/2).✓ Proved
  3. \[ \int\limits_{0}^{2 \pi} 6 \sin{\left(\frac{t}{2} \right)}\, dt = 24 \]
    Integrate the speed (sin(t/2) ≥ 0 on [0, 2π]).✓ Proved
Answer \( 24 \approx 24.00000 \)

✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

20. Area in polar coordinates

Find the area of the region swept by \( \displaystyle r = \theta \) for \( \displaystyle 0 \le \theta \le \pi \).
  1. Area in polar coordinates is ½∫ r² dθ over the angles that trace the region once.
    Reviewed
  2. Here θ runs from 0 to pi.
    Reviewed
  3. \[ \int\limits_{0}^{\pi} \frac{\theta^{2}}{2}\, d\theta = \frac{\pi^{3}}{6} \]
    Integrate.✓ Proved
Answer \( \frac{\pi^{3}}{6} \)

✓ Nihil obstat Lines: 1 proved, 2 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

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