A B C A L C U L U S
Chapter 6
Integration & Accumulation of Change
AP-Style Practice Questions
EASYMEDIUMHARD
Topics 6.1 – 6.10, 6.14AB
+ Extensions: 6.11 IBP · 6.12 Partial Fractions · 6.13 Improper IntegralsBC
Name:Period:
PART ITopics 6.1 – 6.10
Multiple Choice Questions
Show all supporting work on scratch paper. On the AP Exam, Section I is split into a no-calculator and a calculator-allowed part — each question below is labeled accordingly.
Q1EASY6.2 Riemann SumsNo Calculator
The interval $[0,4]$ is divided into four subintervals of equal length. Which expression gives the right Riemann sum approximation for $\displaystyle\int_{0}^{4}f(x)\,dx$?
- (A) $f(0)+f(1)+f(2)+f(3)$
- (B) $f(1)+f(2)+f(3)+f(4)$
- (C) $f(0.5)+f(1.5)+f(2.5)+f(3.5)$
- (D) $\tfrac{1}{2}\bigl[f(0)+2f(1)+2f(2)+2f(3)+f(4)\bigr]$
Q2EASY6.6 PropertiesNo Calculator
If $\displaystyle\int_{0}^{5}f(x)\,dx=12$ and $\displaystyle\int_{0}^{2}f(x)\,dx=3$, then $\displaystyle\int_{2}^{5}f(x)\,dx=$
- (A) $-9$
- (B) $9$
- (C) $15$
- (D) $36$
Q3EASY6.4 FTCNo Calculator
If $F(x)=\displaystyle\int_{1}^{x}t^{2}\,dt$, then $F'(x)=$
- (A) $\dfrac{x^{3}}{3}$
- (B) $x^{2}-1$
- (C) $x^{2}$
- (D) $2x$
Q4MEDIUM6.4 FTC + ChainNo Calculator
If $F(x)=\displaystyle\int_{0}^{x^{2}}\sin t\,dt$, then $F'(x)=$
- (A) $\sin(x^{2})$
- (B) $2x\sin(x^{2})$
- (C) $-\cos(x^{2})+1$
- (D) $\cos(x^{2})\cdot 2x$
Q5EASY6.8 AntiderivativesNo Calculator
$\displaystyle\int (3x^{2}-4x+5)\,dx =$
- (A) $x^{3}-2x^{2}+5x+C$
- (B) $x^{3}-2x^{2}+5+C$
- (C) $6x-4+C$
- (D) $\dfrac{x^{3}}{3}-\dfrac{4x^{2}}{2}+5x+C$
Q6MEDIUM6.9 U-SubstitutionNo Calculator
$\displaystyle\int 2x\,(x^{2}+1)^{4}\,dx =$
- (A) $\dfrac{(x^{2}+1)^{5}}{5}+C$
- (B) $\dfrac{(x^{2}+1)^{5}}{10}+C$
- (C) $2x\cdot\dfrac{(x^{2}+1)^{5}}{5}+C$
- (D) $\dfrac{x^{2}(x^{2}+1)^{5}}{5}+C$
Q7MEDIUM6.7 FTC EvaluationNo Calculator
$\displaystyle\int_{0}^{\pi/2}\cos x\,dx =$
- (A) $0$
- (B) $\dfrac{1}{2}$
- (C) $1$
- (D) $\dfrac{\pi}{2}$
Q8MEDIUM6.6 Geometry of IntegralNo Calculator
The graph of $f$ consists of two line segments (forming a triangle above the $x$-axis with vertices $(-2,0)$, $(0,2)$, $(2,0)$) and a semicircle of radius $2$ below the $x$-axis on $[2,6]$. Find $\displaystyle\int_{-2}^{6}f(x)\,dx$.
- (A) $4-2\pi$
- (B) $4+2\pi$
- (C) $3+2\pi$
- (D) $3-2\pi$
Q9HARD6.9 U-Sub DefiniteNo Calculator
$\displaystyle\int_{0}^{1}\dfrac{x}{(x^{2}+1)^{2}}\,dx =$
- (A) $\dfrac{1}{4}$
- (B) $\dfrac{1}{2}$
- (C) $\dfrac{1}{8}$
- (D) $\dfrac{1}{6}$
Q10MEDIUM6.3 Riemann ↔ IntegralNo Calculator
Which definite integral equals $\displaystyle\lim_{n\to\infty}\sum_{i=1}^{n}\!\left(1+\dfrac{2i}{n}\right)^{2}\!\cdot\dfrac{2}{n}$?
- (A) $\displaystyle\int_{0}^{2}x^{2}\,dx$
- (B) $\displaystyle\int_{1}^{3}x^{2}\,dx$
- (C) $\displaystyle\int_{1}^{2}(1+x)^{2}\,dx$
- (D) $\displaystyle\int_{0}^{1}(1+2x)^{2}\,dx$
Q11HARD6.2 Over/UnderestimateNo Calculator
$f$ is positive, increasing, and concave down on $[a,b]$. Which of the following must be an underestimate of $\displaystyle\int_{a}^{b}f(x)\,dx$?
- (A) Left Riemann sum
- (B) Right Riemann sum
- (C) Trapezoidal sum
- (D) Midpoint Riemann sum
Q12MEDIUM6.10 Long DivisionNo Calculator
$\displaystyle\int \dfrac{x^{2}+1}{x+1}\,dx =$
- (A) $\dfrac{x^{2}}{2}-x+2\ln|x+1|+C$
- (B) $x-\ln|x+1|+C$
- (C) $\dfrac{x^{3}+x}{x^{2}+x}+C$
- (D) $\dfrac{x^{2}}{2}+\ln|x+1|+C$
Q13HARD6.2 / 6.4 AccumulationNo Calculator
Selected values of the differentiable function $f$ are given. Let $g(x)=\displaystyle\int_{0}^{x}f(t)\,dt$.
| $x$ | $0$ | $2$ | $4$ | $6$ | $8$ |
| $f(x)$ | $5$ | $3$ | $-1$ | $-4$ | $-2$ |
Using a midpoint Riemann sum with two subintervals of equal length, the approximation for $g(8)$ is
- (A) $-4$
- (B) $-2$
- (C) $4$
- (D) $12$
Q14MEDIUM6.5 Behavior of $g$No Calculator
Let $g(x)=\displaystyle\int_{0}^{x}f(t)\,dt$, where $f$ is continuous and is positive on $(0,3)$, zero at $x=3$, and negative on $(3,5)$. At what value of $x$ does $g$ attain its maximum on $[0,5]$?
- (A) $0$
- (B) $3$
- (C) $5$
- (D) Cannot be determined
Q15EASY6.1 Accumulation UnitsNo Calculator
Water flows into a tank at a rate $r(t)$ gallons per minute, where $t$ is in minutes. The most appropriate units of $\displaystyle\int_{0}^{10}r(t)\,dt$ are
- (A) gallons per minute
- (B) gallons per minute squared
- (C) gallons
- (D) minutes per gallon
Q16HARD6.10 Completing the SquareNo Calculator
$\displaystyle\int \dfrac{1}{x^{2}+2x+5}\,dx =$
- (A) $\dfrac{1}{2}\arctan\!\left(\dfrac{x+1}{2}\right)+C$
- (B) $\arctan(x+1)+C$
- (C) $\ln|x^{2}+2x+5|+C$
- (D) $\dfrac{1}{4}\ln|x^{2}+2x+5|+C$
Q17MEDIUM6.14 Selecting a TechniqueNo Calculator
Which technique is most appropriate for evaluating $\displaystyle\int x\sec^{2}(x^{2})\,dx$?
- (A) Power rule (direct antidifferentiation)
- (B) $u$-substitution with $u=x^{2}$
- (C) Long division
- (D) Completing the square
Q18MEDIUM6.6 PropertiesNo Calculator
If $\displaystyle\int_{1}^{4}\bigl[\,2f(x)-3\,\bigr]\,dx = 14$ and $\displaystyle\int_{1}^{4}f(x)\,dx = ?$
- (A) $\dfrac{17}{2}$
- (B) $\dfrac{23}{2}$
- (C) $\dfrac{11}{2}$
- (D) $7$
PART IIShow All Work
Free-Response Questions
Free-response answers must include all setup. When using a calculator, present the integral expression with limits and a differential before evaluating. When without a calculator, show antiderivatives, the constant of integration on indefinite integrals, and careful use of substitution.
FRQ 1EASY6.7 / 6.8 / 6.9 EvaluationNo Calculator
Evaluate each of the following. Show all work.
(a) $\displaystyle\int_{1}^{2}(4x^{3}-6x+1)\,dx$
(b) $\displaystyle\int \cos(3x)\,dx$
(c) $\displaystyle\int x\,e^{x^{2}}\,dx$
FRQ 2MEDIUM6.1 / 6.2 / 6.3 ReservoirCalculator
The rate at which water enters a reservoir is modeled by the differentiable function $R(t)$, where $R$ is in thousands of gallons per hour and $t$ is in hours since midnight. Selected values of $R$:
| $t$ (hr) | $0$ | $3$ | $6$ | $9$ | $12$ |
| $R(t)$ | $5.2$ | $6.8$ | $8.1$ | $7.4$ | $4.5$ |
(a) Use a left Riemann sum with the four subintervals shown to approximate $\displaystyle\int_{0}^{12}R(t)\,dt$. Using correct units, explain the meaning of this integral in context.
(b) Use a trapezoidal sum with the four subintervals shown to approximate $\displaystyle\int_{0}^{12}R(t)\,dt$.
(c) Is the left Riemann sum in part (a) an over- or under-estimate? Explain using the behavior of $R$ shown in the table, or state what additional information would be needed to decide.
(d) The reservoir holds $W(t)$ thousand gallons at time $t$. Water leaves the reservoir at a constant rate of $4$ thousand gallons per hour during the $12$-hour period. Write, but do not evaluate, an expression involving an integral for $W(12)$ given $W(0)=80$.
FRQ 3MEDIUM6.4 / 6.5 Accumulation FunctionNo Calculator
The graph of the continuous function $f$ on $[0,8]$ consists of three line segments and a quarter circle of radius $2$, as shown. Let $g(x)=\displaystyle\int_{0}^{x}f(t)\,dt$.
(a) Find $g(2)$, $g(4)$, and $g(8)$.
(b) On what interval(s) is $g$ increasing? Justify.
(c) At what value of $x$ on $[0,8]$ does $g$ attain its absolute maximum? Justify.
(d) Find the $x$-coordinate of each point of inflection of $g$ on $(0,8)$. Justify.
FRQ 4HARD6.8 / 6.9 / 6.10 TechniquesNo Calculator
Evaluate each of the following integrals, showing all algebraic steps. For $u$-substitution problems, clearly state your choice of $u$ and $du$.
(a) $\displaystyle\int \dfrac{2x+3}{x^{2}+3x+5}\,dx$
(b) $\displaystyle\int_{0}^{1}x\sqrt{1-x^{2}}\,dx$
(c) $\displaystyle\int \dfrac{x^{2}+1}{x-2}\,dx$
FRQ 5HARD6.4 / 6.5 / 6.7 Reasoning with $g$No Calculator
Let $f$ be a continuous function on $[-2,8]$, and define $g(x)=\displaystyle\int_{0}^{x}f(t)\,dt$. It is known that $\displaystyle\int_{0}^{3}f(t)\,dt=6$, $\displaystyle\int_{3}^{5}f(t)\,dt=-2$, and $\displaystyle\int_{5}^{8}f(t)\,dt=4$.
(a) Find $g(3)$, $g(5)$, and $g(8)$.
(b) Find $\displaystyle\int_{-1}^{8}\bigl[\,2f(t)+1\,\bigr]\,dt$, given that $\displaystyle\int_{-1}^{0}f(t)\,dt = 1$.
(c) Suppose $f$ is differentiable on $[0,8]$, with $f(0)=2$ and $f(8)=-3$. Let $h(x)=x\cdot f(x)$. Find $\displaystyle\int_{0}^{8}\bigl[\,f(x)+x\,f'(x)\,\bigr]\,dx$.
(d) Let $H(x)=\displaystyle\int_{0}^{x^{2}}f(t)\,dt$. Express $H'(x)$ in terms of $f$ and $x$.
PART III — (BC) EXTENSIONSTopics 6.11, 6.12, 6.13 — BC ONLY
BC-Only Practice
BC ONLY. The following items cover Integration by Parts (Topic 6.11), Linear Partial Fractions (Topic 6.12), and Improper Integrals (Topic 6.13). AB students may skip this section. BC students should be fluent with: (i) IBP $\displaystyle\int u\,dv = uv-\int v\,du$ — pick $u$ via LIATE; (ii) decomposing proper rationals with distinct linear factors as $\dfrac{A}{x-r_1}+\dfrac{B}{x-r_2}+\cdots$; (iii) evaluating improper integrals as limits, including those with interior discontinuities (split first).
Q BC1MEDIUM6.11 IBPBC ONLYNo Calculator
$\displaystyle\int_{0}^{1}x\,e^{x}\,dx=$
- (A) $0$
- (B) $1$
- (C) $e-1$
- (D) $e$
Q BC2MEDIUM6.12 Partial FractionsBC ONLYNo Calculator
The partial-fraction decomposition of $\dfrac{1}{x^{2}-1}$ is
- (A) $\dfrac{1}{x-1}+\dfrac{1}{x+1}$
- (B) $\dfrac{1/2}{x-1}-\dfrac{1/2}{x+1}$
- (C) $\dfrac{1/2}{x-1}+\dfrac{1/2}{x+1}$
- (D) $\dfrac{1}{x-1}-\dfrac{1}{x+1}$
Q BC3EASY6.13 ImproperBC ONLYNo Calculator
$\displaystyle\int_{1}^{\infty}\dfrac{1}{x^{2}}\,dx=$
- (A) $0$
- (B) $1$
- (C) $\infty$ (diverges)
- (D) $\dfrac{1}{2}$
Q BC4MEDIUM6.13 Improper (Compare)BC ONLYNo Calculator
Which of the following improper integrals diverge?
- I. $\displaystyle\int_{1}^{\infty}\dfrac{1}{x}\,dx$
- II. $\displaystyle\int_{1}^{\infty}\dfrac{1}{x^{3/2}}\,dx$
- III. $\displaystyle\int_{0}^{1}\dfrac{1}{\sqrt{x}}\,dx$
- (A) I only
- (B) I and II
- (C) II and III
- (D) I, II, and III
FRQ BC1HARD6.11 IBP (Twice)BC ONLYNo Calculator
Evaluate each integral using integration by parts. State your choice of $u$ and $dv$ at every step.
(a) $\displaystyle\int x^{2}\,e^{x}\,dx$ — apply IBP twice.
(b) $\displaystyle\int_{1}^{e}\ln x\,dx$ — use $u=\ln x$, $dv=dx$.
(c) Briefly explain how the LIATE mnemonic guided your $u$ selection in parts (a) and (b).
FRQ BC2HARD6.12 / 6.13 Partial Fractions + ImproperBC ONLYNo Calculator
Consider $\displaystyle\int_{2}^{\infty}\dfrac{1}{x^{2}-x}\,dx$.
(a) Decompose $\dfrac{1}{x^{2}-x}$ into partial fractions. Show the algebraic system you solve.
(b) Set up the integral as a limit, evaluate the antiderivative, and determine whether the integral converges. If it converges, give the exact value.
(c) Now consider $\displaystyle\int_{0}^{2}\dfrac{1}{(x-1)^{1/3}}\,dx$, which is improper at the interior point $x=1$. Split the integral, evaluate each piece as a one-sided limit, and find the total value (or state divergence). Justify each step.