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Mathematics LibreTexts

6.1E: Exercises for Section 6.1

This page is a draft and is under active development. 

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Exercises 6.1E.1

For the following exercises, determine the area of the region between the two curves in the given figure by integrating over the x-axis.

1. y=x23 and y=1

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Answer

32

2. y=x2 and y=3x+4

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Exercise 6.1E.2

For the following exercises, split the region between the two curves into two smaller regions, then determine the area by integrating over the x-axis. Note that you will have two integrals to solve

1. y=x3 and y=x2+x

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Answer

1312

2. y=cosθ and y=0.5, for 0θπ

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Exercise 6.1E.3

For the following exercises, determine the area of the region between the two curves by integrating over the yaxis.

1. x=y2 and x=9

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Answer

36

2. y=x and x=y2

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Exercises 6.1E.4

For the following exercises, graph the equations and shade the area of the region between the curves. Determine its area by integrating over the x-axis.

1. y=x2 and y=x2+8x

Answer

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243 square units

Solution

Intersecting points:x2+18x=x22x218=2(x)(x9)=0x=0,x=9.\\

Area= 90((x2+18x)x2)dx=90(2x2+18x)dx=243unit2

 

2. y=1x,y=1x2,and x=3

3. y=cosx and y=cos2x on x=[π,π]

Answer

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4

4. y=ex,y=e2x1, and x=0

5. y=ex,y=ex,x=1 and x=1

Answer

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2(e1)2e

6. y=e,y=ex, and y=ex

7. y=|x| and y=x2

Answer

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13

Exercises 6.1E.5

For the following exercises, graph the equations and shade the area of the region between the curves. If necessary, break the region into sub-regions to determine its entire area.

1. y=sin(πx),y=2x,andx>0

2. y=12x,y=x,and y=1

Answer

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344

3. y=sinx and y=cosx over x=[π,π]

4. y=x3 and y=x22nover x=[1,1]

Answer
 

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52

5. y=x2+9 and y=10+2x over x= [1,3]

6. y=x3+3x and y=4x

Answer
 

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\(\displaystyle \frac{1}{2}\

Exercises 6.1E.6

For the following exercises, graph the equations and shade the area of the region between the curves. Determine its area by integrating over the y-axis.

1. x=y3 axnd 3y2

2. x=y and x=y3y

Answer

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92

3. x=3+y2 and x=yy2

4. y2=x and x=y+2

Answer
 

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92

5. x=|y| and 2x=y2+2

6. x=siny,x=cos(2y),y=π/2,and y=π/2

Answer

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332

Exercises 6.1E.7

For the following exercises, graph the equations and shade the area of the region between the curves. Determine its area by integrating over the x-axis or y-axis, whichever seems more convenient.

1. x=y4 and x=y5

2. y=xex,y=ex,x=0, and x=1.

Answer
 

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e2

 

3. y=x6 and y=x4

4. x=y3+2y2+1 and x=y2+1

Answer
 

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274

5. y=|x| and y=x21

6. y=43xand y=1x

Answer
 

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43ln(3)

7. y=sinx,x=π/6,x=π/6, and y=cos3x

8. y=x23x+2 and y=x32x2x+2

Answer
 

This figure is has two graphs. They are the equations y=x^2-3x+2 and y=x^3-2x^2-x+2. The graphs intersect, having region between them shaded.

12

9. y=2cos3(3x),y=1,x=π4,andx=π4

10. y+y3=x and 2y=x

Answer
 

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12

11. y=1x2 and y=x21

12. y=cos1x,y=sin1x,x=1, and x=1

Answer

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2(2π)

Exercises 6.1E.8

For the following exercises, find the exact area of the region bounded by the given equations if possible. If you are unable to determine the intersection points analytically, use a calculator to approximate the intersection points with three decimal places and determine the approximate area of the region.

1. x=ey and y=x2

2. y=x2 and y=1x2

Answer

1.067

3. y=3x2+8x+9 and 3y=x+24

4. x=4y2 and y2=1+x2

Answer

0.852

5. x2=y3 and x=3y

6. y=sin3x+2,y=tanx,x=1.5, and x=1.5

Answer

7.523

7. y=1x2 and y2=x2

8. y=1x2 and y=x2+2x+1

Answer

3π412

9. x=4y2 and x=1+3y+y2

10. y=cosx,y=ex,x=π,andx=0

Answer

1.429

Exercise 6.1E.9

The largest triangle with a base on the x-axis that fits inside the upper half of the unit circle y2+x2=1 is given by y=1+x and y=1x. See the following figure. What is the area inside the semicircle but outside the triangle?

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Answer

Under Construction

Exercise 6.1E.10

A factory selling cell phones has a marginal cost function C(x)=0.01x23x+229, where x represents the number of cell phones, and a marginal revenue function given by R(x)=4292x. Find the area between the graphs of these curves and x=0. What does this area represent?

Answer

$33,333.33 total profit for 200 cell phones sold

Exercise 6.1E.11

An amusement park has a marginal cost function C(x)=1000ex+5, where x represents the number of tickets sold, and a marginal revenue function given by R(x)=600.1x. Find the total profit generated when selling 550 tickets. Use a calculator to determine intersection points, if necessary, to two decimal places.

Answer

Under Construction

Exercise 6.1E.12

The tortoise versus the hare: The speed of the hare is given by the sinusoidal function H(t)=1cos((πt)/2) whereas the speed of the tortoise is T(t)=(1/2)tan1(t/4), where t is time measured in hours and the speed is measured in miles per hour. Find the area between the curves from time t=0 to the first time after one hour when the tortoise and hare are traveling at the same speed. What does it represent? Use a calculator to determine the intersection points, if necessary, accurate to three decimal places.

Answer

3.263 mi represents how far ahead the hare is from the tortoise.

Exercise 6.1E.13

The tortoise versus the hare: The speed of the hare is given by the sinusoidal function H(t)=(1/2)(1/2)cos(2πt) whereas the speed of the tortoise is T(t)=t, where t is time measured in hours and speed is measured in kilometers per hour. If the race is over in 1 hour, who won the race and by how much? Use a calculator to determine the intersection points, if necessary, accurate to three decimal places.

Answer

Under Construction

Exercises 6.1E.14

For the following exercises, find the area between the curves by integrating with respect to x and then with respect to y. Is one method easier than the other? Do you obtain the same answer?

1. y=x2+2x+1 and y=x23x+4

Answer

34324

2. y=x4 and x=y5

3. x=y22 and x=2y

Answer

43

Exercises 6.1E.15

For the following exercises, solve using calculus, then check your answer with geometry.

1. Determine the equations for the sides of the square that touches the unit circle on all four sides, as seen in the following figure. Find the area between the perimeter of this square and the unit circle. Is there another way to solve this without using calculus?

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2. Find the area between the perimeter of the unit circle and the triangle created from y=2x+1,y=12x and y=35, as seen in the following figure. Is there a way to solve this without using calculus?

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Answer

π3225

Contributors and Attributions

  • Gilbert Strang (MIT) and Edwin “Jed” Herman (Harvey Mudd) with many contributing authors. This content by OpenStax is licensed with a CC-BY-SA-NC 4.0 license. Download for free at http://cnx.org.

  • Pamini Thangarajah (Mount Royal University, Calgary, Alberta, Canada)


6.1E: Exercises for Section 6.1 is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by LibreTexts.

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