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AP Calculus AB Quiz

AP Calculus AB Quiz: Area Between Curves Functions Of Y

Practice Area Between Curves Functions Of Y in AP Calculus AB with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

Question 1 / 20

0 of 20 answered

An expression for area between x=y−4x=y-4x=y−4 (left) and x=y2x=y^2x=y2 (right) on 1≤y≤41\le y\le 41≤y≤4 is

Select an answer to continue

What this quiz covers

This quiz focuses on Area Between Curves Functions Of Y, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Calculus AB.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

An expression for area between x=y−4x=y-4x=y−4 (left) and x=y2x=y^2x=y2 (right) on 1≤y≤41\le y\le 41≤y≤4 is

  1. ∫14[y2−(y−4)]dy\displaystyle \int_{1}^{4}\big[y^2-(y-4)\big]dy∫14​[y2−(y−4)]dy (correct answer)
  2. ∫14[(y−4)−y2]dy\displaystyle \int_{1}^{4}\big[(y-4)-y^2\big]dy∫14​[(y−4)−y2]dy
  3. ∫41[y2−(y−4)]dy\displaystyle \int_{4}^{1}\big[y^2-(y-4)\big]dy∫41​[y2−(y−4)]dy
  4. ∫14[(y+4)−y2]dy\displaystyle \int_{1}^{4}\big[(y+4)-y^2\big]dy∫14​[(y+4)−y2]dy
  5. ∫14[y2−(y+4)]dy\displaystyle \int_{1}^{4}\big[y^2-(y+4)\big]dy∫14​[y2−(y+4)]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = y² and the left curve is x = y - 4, so the integrand is y² - (y - 4). The limits of integration are from y = 1 to y = 4, as specified. A tempting distractor is choice B, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 2

Which integral gives the area between x=y2−1x=y^2-1x=y2−1 (left) and x=3yx=3yx=3y (right) for 0≤y≤20\le y\le 20≤y≤2?

  1. ∫02[3y−(y2−1)]dy\displaystyle \int_{0}^{2}\big[3y-(y^2-1)\big]dy∫02​[3y−(y2−1)]dy (correct answer)
  2. ∫02[(y2−1)−3y]dy\displaystyle \int_{0}^{2}\big[(y^2-1)-3y\big]dy∫02​[(y2−1)−3y]dy
  3. ∫20[3y−(y2−1)]dy\displaystyle \int_{2}^{0}\big[3y-(y^2-1)\big]dy∫20​[3y−(y2−1)]dy
  4. ∫02[3y−(y2+1)]dy\displaystyle \int_{0}^{2}\big[3y-(y^2+1)\big]dy∫02​[3y−(y2+1)]dy
  5. ∫02[(3y−1)−(y2−1)]dy\displaystyle \int_{0}^{2}\big[(3y-1)-(y^2-1)\big]dy∫02​[(3y−1)−(y2−1)]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = 3y and the left curve is x = y² - 1, so the integrand is 3y - (y² - 1). The limits of integration are from y = 0 to y = 2, as specified. A tempting distractor is choice B, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 3

Which integral represents the area between x=yx=\sqrt{y}x=y​ (left) and x=y2+1x=\frac{y}{2}+1x=2y​+1 (right) for 0≤y≤40\le y\le 40≤y≤4?

  1. ∫04[y−(y2+1)]dy\displaystyle \int_{0}^{4}\left[\sqrt{y}-\left(\frac{y}{2}+1\right)\right]dy∫04​[y​−(2y​+1)]dy
  2. ∫40[(y2+1)−y]dy\displaystyle \int_{4}^{0}\left[\left(\frac{y}{2}+1\right)-\sqrt{y}\right]dy∫40​[(2y​+1)−y​]dy
  3. ∫04[(y2+1)−y]dy\displaystyle \int_{0}^{4}\left[\left(\frac{y}{2}+1\right)-\sqrt{y}\right]dy∫04​[(2y​+1)−y​]dy (correct answer)
  4. ∫04[(y2−1)−y]dy\displaystyle \int_{0}^{4}\left[\left(\frac{y}{2}-1\right)-\sqrt{y}\right]dy∫04​[(2y​−1)−y​]dy
  5. ∫04[(y2+1)−y+1]dy\displaystyle \int_{0}^{4}\left[\left(\frac{y}{2}+1\right)-\sqrt{y+1}\right]dy∫04​[(2y​+1)−y+1​]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = y/2 + 1 and the left curve is x = √y, so the integrand is (y/2 + 1) - √y. The limits of integration are from y = 0 to y = 4, as specified. A tempting distractor is choice A, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 4

Which integral gives area between x=2y2x=2y^2x=2y2 (left) and x=8x=8x=8 (right) for −2≤y≤2-2\le y\le 2−2≤y≤2?

  1. ∫−22[(2y2)−8]dy\displaystyle \int_{-2}^{2}\big[(2y^2)-8\big]dy∫−22​[(2y2)−8]dy
  2. ∫−22[8−(2y2)]dy\displaystyle \int_{-2}^{2}\big[8-(2y^2)\big]dy∫−22​[8−(2y2)]dy (correct answer)
  3. ∫2−2[8−(2y2)]dy\displaystyle \int_{2}^{-2}\big[8-(2y^2)\big]dy∫2−2​[8−(2y2)]dy
  4. ∫−22[8−(y2)]dy\displaystyle \int_{-2}^{2}\big[8-(y^2)\big]dy∫−22​[8−(y2)]dy
  5. ∫−22[8−(2y)]dy\displaystyle \int_{-2}^{2}\big[8-(2y)\big]dy∫−22​[8−(2y)]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = 8 and the left curve is x = 2y², so the integrand is 8 - 2y². The limits of integration are from y = -2 to y = 2, as specified. A tempting distractor is choice A, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 5

Set up the area between x=ln⁡(y+1)+2x=\ln(y+1)+2x=ln(y+1)+2 (right) and x=1x=1x=1 (left) for 0≤y≤30\le y\le 30≤y≤3.

  1. ∫03[1−(ln⁡(y+1)+2)]dy\displaystyle \int_{0}^{3}\big[1-(\ln(y+1)+2)\big]dy∫03​[1−(ln(y+1)+2)]dy
  2. ∫30[(ln⁡(y+1)+2)−1]dy\displaystyle \int_{3}^{0}\big[(\ln(y+1)+2)-1\big]dy∫30​[(ln(y+1)+2)−1]dy
  3. ∫03[(ln⁡(y+1)+2)−1]dy\displaystyle \int_{0}^{3}\big[(\ln(y+1)+2)-1\big]dy∫03​[(ln(y+1)+2)−1]dy (correct answer)
  4. ∫03[(ln⁡(y−1)+2)−1]dy\displaystyle \int_{0}^{3}\big[(\ln(y-1)+2)-1\big]dy∫03​[(ln(y−1)+2)−1]dy
  5. ∫03[(ln⁡(y+1)−2)−1]dy\displaystyle \int_{0}^{3}\big[(\ln(y+1)-2)-1\big]dy∫03​[(ln(y+1)−2)−1]dy

Explanation: This problem tests the skill of finding areas between curves by integrating with respect to y. The area is given by the integral from the lower to upper y-value of (x_right - x_left) dy. Here, x = ln(y+1) + 2 is the right curve and x = 1 is the left curve, so the integrand is (ln(y+1) + 2) - 1. The limits are from y=0 to y=3, matching choice C. A tempting distractor is choice A, which subtracts left minus right, yielding a negative value instead of the positive area. Always evaluate the functions at a point within the interval to confirm which curve is on the right.

Question 6

Which integral gives the area between x=y+12x=\frac{y+1}{2}x=2y+1​ (right) and x=y−2x=y-2x=y−2 (left) for −1≤y≤3-1\le y\le 3−1≤y≤3?

  1. ∫−13[y+12−(y−2)]dy\displaystyle \int_{-1}^{3}\left[\frac{y+1}{2}-(y-2)\right]dy∫−13​[2y+1​−(y−2)]dy (correct answer)
  2. ∫−13[(y−2)−y+12]dy\displaystyle \int_{-1}^{3}\left[(y-2)-\frac{y+1}{2}\right]dy∫−13​[(y−2)−2y+1​]dy
  3. ∫3−1[y+12−(y−2)]dy\displaystyle \int_{3}^{-1}\left[\frac{y+1}{2}-(y-2)\right]dy∫3−1​[2y+1​−(y−2)]dy
  4. ∫−13[y−12−(y−2)]dy\displaystyle \int_{-1}^{3}\left[\frac{y-1}{2}-(y-2)\right]dy∫−13​[2y−1​−(y−2)]dy
  5. ∫−13[y+12−(y+2)]dy\displaystyle \int_{-1}^{3}\left[\frac{y+1}{2}-(y+2)\right]dy∫−13​[2y+1​−(y+2)]dy

Explanation: This problem tests the skill of finding areas between curves by integrating with respect to y. The area is given by the integral from the lower to upper y-value of (x_right - x_left) dy. Here, x = (y+1)/2 is the right curve and x = y-2 is the left curve, so the integrand is (y+1)/2 - (y-2). The limits are from y=-1 to y=3, matching choice A. A tempting distractor is choice B, which subtracts left minus right, yielding a negative value instead of the positive area. Always evaluate the functions at a point within the interval to confirm which curve is on the right.

Question 7

Which integral gives the area between x=2y+1x=2y+1x=2y+1 (left) and x=y2+3x=y^2+3x=y2+3 (right) from y=−1y=-1y=−1 to y=2y=2y=2?

  1. ∫−12[(2y+1)−(y2+3)] dy\displaystyle \int_{-1}^{2}\big[(2y+1)-(y^2+3)\big]\,dy∫−12​[(2y+1)−(y2+3)]dy
  2. ∫−12[(y2+3)−(2y+1)] dy\displaystyle \int_{-1}^{2}\big[(y^2+3)-(2y+1)\big]\,dy∫−12​[(y2+3)−(2y+1)]dy (correct answer)
  3. ∫−21[(y2+3)−(2y+1)] dy\displaystyle \int_{-2}^{1}\big[(y^2+3)-(2y+1)\big]\,dy∫−21​[(y2+3)−(2y+1)]dy
  4. ∫−12[(y2−3)−(2y+1)] dy\displaystyle \int_{-1}^{2}\big[(y^2-3)-(2y+1)\big]\,dy∫−12​[(y2−3)−(2y+1)]dy
  5. ∫−12[(y2+3)−(2y−1)] dy\displaystyle \int_{-1}^{2}\big[(y^2+3)-(2y-1)\big]\,dy∫−12​[(y2+3)−(2y−1)]dy

Explanation: This question requires setting up an area integral with respect to y using the fundamental principle of right minus left. When integrating along the y-axis, we subtract the left boundary function from the right boundary function to get positive area. The problem states that x = 2y + 1 is on the left and x = y² + 3 is on the right, meaning we need (y² + 3) - (2y + 1) as our integrand. Choice A incorrectly uses (2y + 1) - (y² + 3), which would yield negative area since it subtracts the rightmost function from the leftmost. To verify which function is truly on the right, pick a y-value like y = 0: the left curve gives x = 1 while the right curve gives x = 3, confirming our setup.

Question 8

Set up the dydydy integral for area between x=ln⁡(y+2)x=\ln(y+2)x=ln(y+2) (left) and x=2x=2x=2 (right) on −1≤y≤2-1 \le y \le 2−1≤y≤2.

  1. ∫−12[ln⁡(y+2)−2] dy\displaystyle \int_{-1}^{2}\big[\ln(y+2)-2\big]\,dy∫−12​[ln(y+2)−2]dy
  2. ∫−12[2−ln⁡(y+2)] dy\displaystyle \int_{-1}^{2}\big[2-\ln(y+2)\big]\,dy∫−12​[2−ln(y+2)]dy (correct answer)
  3. ∫−21[2−ln⁡(y+2)] dy\displaystyle \int_{-2}^{1}\big[2-\ln(y+2)\big]\,dy∫−21​[2−ln(y+2)]dy
  4. ∫−12[2−ln⁡(y−2)] dy\displaystyle \int_{-1}^{2}\big[2-\ln(y-2)\big]\,dy∫−12​[2−ln(y−2)]dy
  5. ∫−12[3−ln⁡(y+2)] dy\displaystyle \int_{-1}^{2}\big[3-\ln(y+2)\big]\,dy∫−12​[3−ln(y+2)]dy

Explanation: This question tests your ability to set up area integrals with respect to y, applying the fundamental right-minus-left subtraction principle. When computing area using dy integration, we must subtract the left boundary function from the right boundary function to obtain positive area. The problem identifies x=ln⁡(y+2)x = \ln(y + 2)x=ln(y+2) as the left curve and x=2x = 2x=2 as the right curve, so our integrand becomes 2−ln⁡(y+2)2 - \ln(y + 2)2−ln(y+2). Choice A incorrectly uses ln⁡(y+2)−2\ln(y + 2) - 2ln(y+2)−2, which reverses the subtraction and would yield negative area—a typical error when students forget to consider relative positions. To confirm the ordering, evaluate at y=0y = 0y=0: the left curve gives x=ln⁡(2)≈0.693x = \ln(2) \approx 0.693x=ln(2)≈0.693 while the right curve gives x=2x = 2x=2, verifying that the constant function x=2x = 2x=2 is indeed to the right.

Question 9

Set up the area integral (in yyy) between x=−y2+4x=-y^2+4x=−y2+4 (right) and x=y−2x=y-2x=y−2 (left) for 0≤y≤30\le y\le 30≤y≤3.

  1. ∫03[(y−2)−(−y2+4)] dy\displaystyle \int_{0}^{3}\big[(y-2)-(-y^2+4)\big]\,dy∫03​[(y−2)−(−y2+4)]dy
  2. ∫03[(−y2+4)−(y−2)] dy\displaystyle \int_{0}^{3}\big[(-y^2+4)-(y-2)\big]\,dy∫03​[(−y2+4)−(y−2)]dy (correct answer)
  3. ∫03[(−y2−4)−(y−2)] dy\displaystyle \int_{0}^{3}\big[(-y^2-4)-(y-2)\big]\,dy∫03​[(−y2−4)−(y−2)]dy
  4. ∫−30[(−y2+4)−(y−2)] dy\displaystyle \int_{-3}^{0}\big[(-y^2+4)-(y-2)\big]\,dy∫−30​[(−y2+4)−(y−2)]dy
  5. ∫03[(−y2+4)−(y+2)] dy\displaystyle \int_{0}^{3}\big[(-y^2+4)-(y+2)\big]\,dy∫03​[(−y2+4)−(y+2)]dy

Explanation: This problem tests your understanding of area integrals with respect to y, specifically the right-minus-left subtraction order. When finding area between curves using dy integration, we always compute (right function) - (left function) where right means larger x-values. The problem identifies x = -y² + 4 as the right curve and x = y - 2 as the left curve, so our integrand must be (-y² + 4) - (y - 2). Choice A reverses this order to (y - 2) - (-y² + 4), which would produce a negative result—a frequent error when students mechanically subtract without considering position. To remember the correct order, visualize or test: at y = 1, the left curve gives x = -1 while the right curve gives x = 3, confirming that -y² + 4 is indeed rightmost.

Question 10

Which integral represents the area between x=4x=4x=4 (right) and x=sin⁡yx=\sin yx=siny (left) for 0≤y≤π0\le y\le \pi0≤y≤π?

  1. ∫0π[sin⁡y−4]dy\displaystyle \int_{0}^{\pi}\big[\sin y-4\big]dy∫0π​[siny−4]dy
  2. ∫π0[4−sin⁡y]dy\displaystyle \int_{\pi}^{0}\big[4-\sin y\big]dy∫π0​[4−siny]dy
  3. ∫0π[4−sin⁡y]dy\displaystyle \int_{0}^{\pi}\big[4-\sin y\big]dy∫0π​[4−siny]dy (correct answer)
  4. ∫0π[4−cos⁡y]dy\displaystyle \int_{0}^{\pi}\big[4-\cos y\big]dy∫0π​[4−cosy]dy
  5. ∫0π[4+sin⁡y]dy\displaystyle \int_{0}^{\pi}\big[4+\sin y\big]dy∫0π​[4+siny]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = 4 and the left curve is x = sin y, so the integrand is 4 - sin y. The limits of integration are from y = 0 to y = π, as specified. A tempting distractor is choice A, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 11

Which integral gives the area between x=y3x=\frac{y}{3}x=3y​ (left) and x=9y+3x=\frac{9}{y+3}x=y+39​ (right) for 0≤y≤30\le y\le 30≤y≤3?

  1. ∫03[y3−9y+3]dy\displaystyle \int_{0}^{3}\left[\frac{y}{3}-\frac{9}{y+3}\right]dy∫03​[3y​−y+39​]dy
  2. ∫03[9y+3−y3]dy\displaystyle \int_{0}^{3}\left[\frac{9}{y+3}-\frac{y}{3}\right]dy∫03​[y+39​−3y​]dy (correct answer)
  3. ∫30[9y+3−y3]dy\displaystyle \int_{3}^{0}\left[\frac{9}{y+3}-\frac{y}{3}\right]dy∫30​[y+39​−3y​]dy
  4. ∫03[9y−3−y3]dy\displaystyle \int_{0}^{3}\left[\frac{9}{y-3}-\frac{y}{3}\right]dy∫03​[y−39​−3y​]dy
  5. ∫03[9y+3−3y]dy\displaystyle \int_{0}^{3}\left[\frac{9}{y+3}-\frac{3}{y}\right]dy∫03​[y+39​−y3​]dy

Explanation: This problem tests the skill of finding areas between curves by integrating with respect to y. The area is given by the integral from the lower to upper y-value of (x_right - x_left) dy. Here, x = 9/(y+3) is the right curve and x = y/3 is the left curve, so the integrand is 9/(y+3) - y/3. The limits are from y=0 to y=3, matching choice B. A tempting distractor is choice A, which subtracts left minus right, yielding a negative value instead of the positive area. Always evaluate the functions at a point within the interval to confirm which curve is on the right.

Question 12

Find an area expression between x=3−y2x=3-y^2x=3−y2 (left) and x=5x=5x=5 (right) for −1≤y≤1-1 \le y \le 1−1≤y≤1.

  1. ∫−11[(3−y2)−5]dy\displaystyle \int_{-1}^{1}\big[(3-y^2)-5\big]dy∫−11​[(3−y2)−5]dy
  2. ∫−11[5−(3−y2)]dy\displaystyle \int_{-1}^{1}\big[5-(3-y^2)\big]dy∫−11​[5−(3−y2)]dy (correct answer)
  3. ∫1−1[5−(3−y2)]dy\displaystyle \int_{1}^{-1}\big[5-(3-y^2)\big]dy∫1−1​[5−(3−y2)]dy
  4. ∫−11[5−(3+y2)]dy\displaystyle \int_{-1}^{1}\big[5-(3+y^2)\big]dy∫−11​[5−(3+y2)]dy
  5. ∫−11[5−(3−y)]dy\displaystyle \int_{-1}^{1}\big[5-(3-y)\big]dy∫−11​[5−(3−y)]dy

Explanation: This problem tests the skill of finding areas between curves by integrating with respect to y. The area is given by the integral from the lower to upper y-value of (xright−xleft) dy(x_{\text{right}} - x_{\text{left}}) \, dy(xright​−xleft​)dy. Here, x=5x = 5x=5 is the right curve and x=3−y2x = 3 - y^2x=3−y2 is the left curve, so the integrand is 5−(3−y2)5 - (3 - y^2)5−(3−y2). The limits are from y=−1y=-1y=−1 to y=1y=1y=1, matching choice B. A tempting distractor is choice A, which subtracts left minus right, yielding a negative value instead of the positive area. Always evaluate the functions at a point within the interval to confirm which curve is on the right.

Question 13

Which integral represents area between x=1−yx=1-yx=1−y (left) and x=3+y2x=3+y^2x=3+y2 (right) for −2≤y≤1-2\le y\le 1−2≤y≤1?

  1. ∫−21[(1−y)−(3+y2)]dy\displaystyle \int_{-2}^{1}\big[(1-y)-(3+y^2)\big]dy∫−21​[(1−y)−(3+y2)]dy
  2. ∫1−2[(3+y2)−(1−y)]dy\displaystyle \int_{1}^{-2}\big[(3+y^2)-(1-y)\big]dy∫1−2​[(3+y2)−(1−y)]dy
  3. ∫−21[(3+y2)−(1−y)]dy\displaystyle \int_{-2}^{1}\big[(3+y^2)-(1-y)\big]dy∫−21​[(3+y2)−(1−y)]dy (correct answer)
  4. ∫−21[(3−y2)−(1−y)]dy\displaystyle \int_{-2}^{1}\big[(3-y^2)-(1-y)\big]dy∫−21​[(3−y2)−(1−y)]dy
  5. ∫−21[(3+y2)−(1+y)]dy\displaystyle \int_{-2}^{1}\big[(3+y^2)-(1+y)\big]dy∫−21​[(3+y2)−(1+y)]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = 3 + y² and the left curve is x = 1 - y, so the integrand is (3 + y²) - (1 - y). The limits of integration are from y = -2 to y = 1, as specified. A tempting distractor is choice A, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 14

Which integral represents the area between x=y2x=y^2x=y2 (right) and x=y2−4x=y^2-4x=y2−4 (left) for −2≤y≤2-2\le y\le 2−2≤y≤2?

  1. ∫−22[(y2−4)−y2]dy\displaystyle \int_{-2}^{2}\big[(y^2-4)-y^2\big]dy∫−22​[(y2−4)−y2]dy
  2. ∫2−2[y2−(y2−4)]dy\displaystyle \int_{2}^{-2}\big[y^2-(y^2-4)\big]dy∫2−2​[y2−(y2−4)]dy
  3. ∫−22[y2−(y2−4)]dy\displaystyle \int_{-2}^{2}\big[y^2-(y^2-4)\big]dy∫−22​[y2−(y2−4)]dy (correct answer)
  4. ∫−22[y2−(y2+4)]dy\displaystyle \int_{-2}^{2}\big[y^2-(y^2+4)\big]dy∫−22​[y2−(y2+4)]dy
  5. ∫−22[(y2−4)−(y2+4)]dy\displaystyle \int_{-2}^{2}\big[(y^2-4)-(y^2+4)\big]dy∫−22​[(y2−4)−(y2+4)]dy

Explanation: This problem tests the skill of finding areas between curves by integrating with respect to y. The area is given by the integral from the lower to upper y-value of (x_right - x_left) dy. Here, x = y^2 is the right curve and x = y^2 - 4 is the left curve, so the integrand is y^2 - (y^2 - 4). The limits are from y=-2 to y=2, matching choice C. A tempting distractor is choice A, which subtracts left minus right, yielding a negative value instead of the positive area. Always evaluate the functions at a point within the interval to confirm which curve is on the right.

Question 15

Find an area setup between x=1x=1x=1 (left) and x=y2+1x=y^2+1x=y2+1 (right) for −3≤y≤3-3\le y\le 3−3≤y≤3.

  1. ∫−33[(y2+1)−1]dy\displaystyle \int_{-3}^{3}\big[(y^2+1)-1\big]dy∫−33​[(y2+1)−1]dy (correct answer)
  2. ∫−33[1−(y2+1)]dy\displaystyle \int_{-3}^{3}\big[1-(y^2+1)\big]dy∫−33​[1−(y2+1)]dy
  3. ∫3−3[(y2+1)−1]dy\displaystyle \int_{3}^{-3}\big[(y^2+1)-1\big]dy∫3−3​[(y2+1)−1]dy
  4. ∫−33[(y2−1)−1]dy\displaystyle \int_{-3}^{3}\big[(y^2-1)-1\big]dy∫−33​[(y2−1)−1]dy
  5. ∫−33[(y+1)−1]dy\displaystyle \int_{-3}^{3}\big[(y+1)-1\big]dy∫−33​[(y+1)−1]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = y² + 1 and the left curve is x = 1, so the integrand is (y² + 1) - 1. The limits of integration are from y = -3 to y = 3, as specified. A tempting distractor is choice B, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 16

Set up the area between x=2cos⁡yx=2\cos yx=2cosy (left) and x=3x=3x=3 (right) for −π2≤y≤π2-\frac{\pi}{2}\le y\le \frac{\pi}{2}−2π​≤y≤2π​.

  1. ∫−π/2π/2[2cos⁡y−3]dy\displaystyle \int_{-\pi/2}^{\pi/2}\big[2\cos y-3\big]dy∫−π/2π/2​[2cosy−3]dy
  2. ∫π/2−π/2[3−2cos⁡y]dy\displaystyle \int_{\pi/2}^{-\pi/2}\big[3-2\cos y\big]dy∫π/2−π/2​[3−2cosy]dy
  3. ∫−π/2π/2[3−2cos⁡y]dy\displaystyle \int_{-\pi/2}^{\pi/2}\big[3-2\cos y\big]dy∫−π/2π/2​[3−2cosy]dy (correct answer)
  4. ∫−π/2π/2[3−2sin⁡y]dy\displaystyle \int_{-\pi/2}^{\pi/2}\big[3-2\sin y\big]dy∫−π/2π/2​[3−2siny]dy
  5. ∫−π/2π/2[3+2cos⁡y]dy\displaystyle \int_{-\pi/2}^{\pi/2}\big[3+2\cos y\big]dy∫−π/2π/2​[3+2cosy]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x=3x = 3x=3 and the left curve is x=2cos⁡yx = 2 \cos yx=2cosy, so the integrand is 3−2cos⁡y3 - 2 \cos y3−2cosy. The limits of integration are from y=−π2y = -\frac{\pi}{2}y=−2π​ to y=π2y = \frac{\pi}{2}y=2π​, as specified. A tempting distractor is choice A, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 17

Set up the area between x=y3+2x=y^3+2x=y3+2 (right) and x=yx=yx=y (left) on −1≤y≤2-1 \le y \le 2−1≤y≤2.

  1. ∫−12[(y3+2)−y]dy\displaystyle \int_{-1}^{2}\big[(y^3+2)-y\big]dy∫−12​[(y3+2)−y]dy (correct answer)
  2. ∫−12[y−(y3+2)]dy\displaystyle \int_{-1}^{2}\big[y-(y^3+2)\big]dy∫−12​[y−(y3+2)]dy
  3. ∫2−1[(y3+2)−y]dy\displaystyle \int_{2}^{-1}\big[(y^3+2)-y\big]dy∫2−1​[(y3+2)−y]dy
  4. ∫−12[(y3−2)−y]dy\displaystyle \int_{-1}^{2}\big[(y^3-2)-y\big]dy∫−12​[(y3−2)−y]dy
  5. ∫−12[(y2+2)−y]dy\displaystyle \int_{-1}^{2}\big[(y^2+2)-y\big]dy∫−12​[(y2+2)−y]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x=y3+2x = y^3 + 2x=y3+2 and the left curve is x=yx = yx=y, so the integrand is (y3+2)−y(y^3 + 2) - y(y3+2)−y. The limits of integration are from y=−1y = -1y=−1 to y=2y = 2y=2, as specified. A tempting distractor is choice B, which reverses the order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.

Question 18

Find the area setup (with respect to yyy) between x=y2−1x=y^2-1x=y2−1 (left) and x=3−yx=3-yx=3−y (right) for −1≤y≤2-1 \le y \le 2−1≤y≤2.

  1. ∫−12[(3−y)−(y2−1)] dy\displaystyle \int_{-1}^{2}\big[(3-y)-(y^2-1)\big]\,dy∫−12​[(3−y)−(y2−1)]dy (correct answer)
  2. ∫−12[(y2−1)−(3−y)] dy\displaystyle \int_{-1}^{2}\big[(y^2-1)-(3-y)\big]\,dy∫−12​[(y2−1)−(3−y)]dy
  3. ∫−21[(3−y)−(y2−1)] dy\displaystyle \int_{-2}^{1}\big[(3-y)-(y^2-1)\big]\,dy∫−21​[(3−y)−(y2−1)]dy
  4. ∫−12[(3+y)−(y2−1)] dy\displaystyle \int_{-1}^{2}\big[(3+y)-(y^2-1)\big]\,dy∫−12​[(3+y)−(y2−1)]dy
  5. ∫−12[(3−y)−(y2+1)] dy\displaystyle \int_{-1}^{2}\big[(3-y)-(y^2+1)\big]\,dy∫−12​[(3−y)−(y2+1)]dy

Explanation: This problem tests your ability to set up area integrals with respect to y by identifying which function is on the right versus left. When integrating with respect to y, we use the formula (right function) - (left function), where "right" means larger x-values and "left" means smaller x-values. The problem explicitly tells us that x=y2−1x = y^2 - 1x=y2−1 is on the left and x=3−yx = 3 - yx=3−y is on the right, so we need (3−y)−(y2−1)(3 - y) - (y^2 - 1)(3−y)−(y2−1) in our integrand. Choice B reverses this subtraction, which would give a negative area—a common mistake when students forget the right-minus-left rule. To avoid confusion, always sketch the curves or evaluate at a test point: at y=0y = 0y=0, the left curve gives x=−1x = -1x=−1 and the right curve gives x=3x = 3x=3, confirming that 3−y3 - y3−y is indeed to the right.

Question 19

Set up the area (in yyy) between x=2−yx=2-yx=2−y (left) and x=4−yx=\sqrt{4-y}x=4−y​ (right) for 0≤y≤30\le y\le 30≤y≤3.

  1. ∫03[(2−y)−4−y] dy\displaystyle \int_{0}^{3}\big[(2-y)-\sqrt{4-y}\big]\,dy∫03​[(2−y)−4−y​]dy
  2. ∫03[4−y−(2−y)] dy\displaystyle \int_{0}^{3}\big[\sqrt{4-y}-(2-y)\big]\,dy∫03​[4−y​−(2−y)]dy (correct answer)
  3. ∫04[4−y−(2−y)] dy\displaystyle \int_{0}^{4}\big[\sqrt{4-y}-(2-y)\big]\,dy∫04​[4−y​−(2−y)]dy
  4. ∫−30[4−y−(2−y)] dy\displaystyle \int_{-3}^{0}\big[\sqrt{4-y}-(2-y)\big]\,dy∫−30​[4−y​−(2−y)]dy
  5. ∫03[4+y−(2−y)] dy\displaystyle \int_{0}^{3}\big[\sqrt{4+y}-(2-y)\big]\,dy∫03​[4+y​−(2−y)]dy

Explanation: This problem tests your ability to construct area integrals with respect to y using the fundamental right-minus-left principle. For dy integration, we always compute (right function) - (left function) where right indicates the function with larger x-values at each y-level. Given that x = 2−y2 - y2−y is on the left and x = 4−y\sqrt{4 - y}4−y​ is on the right, the correct integrand is 4−y−(2−y)\sqrt{4 - y} - (2 - y)4−y​−(2−y). Choice A reverses this to (2−y)−4−y(2 - y) - \sqrt{4 - y}(2−y)−4−y​, which would produce negative area—a frequent error when students mechanically subtract without considering relative positions. To confirm the ordering, evaluate at y=0y = 0y=0: the left curve gives x=2x = 2x=2 while the right curve gives x=2x = 2x=2 as well, but at y=3y = 3y=3: left gives x=−1x = -1x=−1 while right gives x=1x = 1x=1, verifying that 4−y\sqrt{4 - y}4−y​ is indeed rightmost.

Question 20

An integral for the area between x=1y+1x=\frac{1}{y+1}x=y+11​ (right) and x=0x=0x=0 (left) on 1≤y≤31\le y\le 31≤y≤3 is

  1. ∫13[0−1y+1]dy\displaystyle \int_{1}^{3}\left[0-\frac{1}{y+1}\right]dy∫13​[0−y+11​]dy
  2. ∫31[1y+1−0]dy\displaystyle \int_{3}^{1}\left[\frac{1}{y+1}-0\right]dy∫31​[y+11​−0]dy
  3. ∫13[1y+1−0]dy\displaystyle \int_{1}^{3}\left[\frac{1}{y+1}-0\right]dy∫13​[y+11​−0]dy (correct answer)
  4. ∫13[1y−1−0]dy\displaystyle \int_{1}^{3}\left[\frac{1}{y-1}-0\right]dy∫13​[y−11​−0]dy
  5. ∫13[11−y−0]dy\displaystyle \int_{1}^{3}\left[\frac{1}{1-y}-0\right]dy∫13​[1−y1​−0]dy

Explanation: This problem requires using integration with respect to y to find the area between curves given as functions of y. The area is calculated by integrating the difference between the right curve and the left curve over the given y-interval. Here, the right curve is x = 1/(y + 1) and the left curve is x = 0, so the integrand is 1/(y + 1) - 0. The limits of integration are from y = 1 to y = 3, as specified. A tempting distractor is choice A, which subtracts in the wrong order and gives negative area. Always determine which curve is on the right by evaluating their x-values at a test point in the interval.