Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 15: Multiple Integration

107 problems · 2 figures

15.1.1 §15.1 source ↗

Compute ∫02∫041+xdydx⁠.

Answer

16

15.1.2 §15.1 source ↗

Compute ∫−11∫02x+ydydx⁠.

Answer

4

15.1.3 §15.1 source ↗

Compute ∫12∫0yxydxdy⁠.

Answer

15/8

15.1.4 §15.1 source ↗

Compute ∫01∫y2/2ydxdy⁠.

Answer

1/2

15.1.5 §15.1 source ↗

Compute ∫12∫1xx2y2dydx⁠.

Answer

5/6

15.1.6 §15.1 source ↗

Compute ∫01∫0x2yexdydx⁠.

Answer

12−65/(2e)⁠.

15.1.7 §15.1 source ↗

Compute ∫0π/2∫0x2xcos⁡ydydx⁠.

Answer

1/2

15.1.8 §15.1 source ↗

Compute ∫0π/2 ∫0cos⁡θr2(cos⁡θ− r)drdθ⁠.

Answer

π/64

15.1.9 §15.1 source ↗

Compute: ∫01∫y1x3+1dxdy⁠.

Answer

(2/9)23/2−(2/9)

15.1.10 §15.1 source ↗

Compute: ∫01∫y21ysin⁡(x2)dxdy⁠.

Answer

(1−cos⁡(1))/4

15.1.11 §15.1 source ↗

Compute: ∫01∫x21x1+y2dydx

Answer

(22−1)/6

15.1.12 §15.1 source ↗

Compute: ∫01∫0y21−x2dxdy

Answer

π−2

15.1.13 §15.1 source ↗

Compute: ∫01∫3y3ex2dxdy

Answer

(e9−1)/6

15.1.14 §15.1 source ↗

Compute ∫−11∫01−x2x2−ydydx⁠.

Answer

415−π4

15.1.15 §15.1 source ↗

Compute ∫02/2∫−1−2x21−2x2xdydx⁠.

Answer

1/3

15.1.16 §15.1 source ↗

Evaluate ∫∫⁡x2dA over the region in the first quadrant bounded by the hyperbola xy=16 and the lines y=x⁠, y=0⁠, and x=8⁠.

Answer

448

15.1.17 §15.1 source ↗

Find the volume below z=1−y above the region −1≤x≤1⁠, 0≤y≤1−x2⁠.

Answer

4/5

15.1.18 §15.1 source ↗

Find the volume bounded by z=x2+y2 and z=4⁠.

Answer

8π

15.1.19 §15.1 source ↗

Find the volume in the first octant bounded by y2=4−x and y=2z⁠.

Answer

2

15.1.20 §15.1 source ↗

Find the volume in the first octant bounded by y2=4x⁠, 2x+y=4⁠, z=y⁠, and y=0⁠.

Answer

5/3

15.1.21 §15.1 source ↗

Find the volume in the first octant bounded by x+y+z=9⁠, 2x+3y=18⁠, and x+3y=9⁠.

Answer

81/2

15.1.22 §15.1 source ↗

Find the volume in the first octant bounded by x2+y2=a2 and z=x+y⁠.

Answer

2a3/3

15.1.23 §15.1 source ↗

Find the volume bounded by 4x2+y2=4z and z=2⁠.

Answer

4π

15.1.24 §15.1 source ↗

Find the volume bounded by z=x2+y2 and z=y⁠.

Answer

π/32

15.1.25 §15.1 source ↗

Find the volume under the surface z=xy above the triangle with vertices (1,1,0)⁠, (4,1,0)⁠, (1,2,0)⁠.

Answer

31/8

15.1.26 §15.1 source ↗

Find the volume enclosed by y=x2⁠, y=4⁠, z=x2⁠, z=0⁠.

Answer

128/15

15.1.27 §15.1 source ↗

A swimming pool is circular with a 40 meter diameter. The depth is constant along east-west lines and increases linearly from 2 meters at the south end to 7 meters at the north end. Find the volume of the pool.

Answer

1800π m3

15.1.28 §15.1 source ↗

Find the average value of f(x,y)=eyx+ey on the rectangle with vertices (0,0)⁠, (4,0⁠), (4,1) and (0,1)⁠.

Answer

(e2+8e+16)15e+4− 553− e5/215+ 115

15.1.30 §15.1 source ↗

Three cylinders of radius 1 intersect at right angles at the origin, as shown in figure 15.1.6. Find the volume contained inside all three cylinders.

Figure 15.1.6 in the book ↗
Intersection of three cylinders.

Answer

16−82

15.1.32 §15.1 source ↗

Reverse the order of integration on each of the following integrals

a. ∫09∫09−yf(x,y)dxdy

b. ∫12∫0ln⁡xf(x,y)dydx

c. ∫01 ∫arcsin⁡yπ/2f(x, y)dxdy

d. ∫01∫4x4f(x,y)dydx

e. ∫03∫09−y2f(x,y)dxdy

Answer

(a) ∫03∫09−x2f(x,y)dydx (b) ∫0e2∫ey2f(x,y)dxdy (c) ∫0π/2∫0sin⁡xf(x,y)dydx (d) ∫04∫0y/4f(x,y)dxdy (e) ∫03∫09−x2f(x,y)dydx

15.2.1 §15.2 source ↗

Find the volume above the x⁠-⁠y plane, under the surface r2=2z⁠, and inside r=2⁠.

Answer

4π

15.2.2 §15.2 source ↗

Find the volume inside both r=1 and r2+z2=4⁠.

Answer

32π/3−43π

15.2.3 §15.2 source ↗

Find the volume below z=1−r2 and above the top half of the cone z=r⁠.

Answer

(2−2)π/3

15.2.4 §15.2 source ↗

Find the volume below z=r⁠, above the x⁠-⁠y plane, and inside r=cos⁡θ⁠.

Answer

4/9

15.2.5 §15.2 source ↗

Find the volume below z=r⁠, above the x⁠-⁠y plane, and inside r=1+cos⁡θ⁠.

Answer

5π/3

15.2.6 §15.2 source ↗

Find the volume between x2+y2=z2 and x2+y2=z⁠.

Answer

π/6

15.2.7 §15.2 source ↗

Find the area inside r=1+sin⁡θ and outside r=2sin⁡θ⁠.

Answer

π/2

15.2.8 §15.2 source ↗

Find the area inside both r=2sin⁡θ and r=2cos⁡θ⁠.

Answer

π/2−1

15.2.9 §15.2 source ↗

Find the area inside the four-leaf rose r=cos⁡(2θ) and outside r=1/2⁠.

Answer

3/4+π/6

15.2.10 §15.2 source ↗

Find the area inside the cardioid r=2(1+cos⁡θ) and outside r=2⁠.

Answer

8+π

15.2.11 §15.2 source ↗

Find the area of one loop of the three-leaf rose r=cos⁡(3θ)⁠.

Answer

π/12

15.2.12 §15.2 source ↗

Compute ∫−33 ∫09−x2sin⁡(x2+ y2)dydx by converting to cylindrical coordinates.

Answer

(1−cos⁡(9))π/2

15.2.13 §15.2 source ↗

Compute ∫0a∫−a2−x20x2ydydx by converting to cylindrical coordinates.

Answer

−a5/15

15.2.14 §15.2 source ↗

Find the volume under z=y2+x+2 above the region x2+y2≤4

Answer

12π

15.2.15 §15.2 source ↗

Find the volume between z=x2y3 and z=1 above the region x2+y2≤1

Answer

π

15.2.16 §15.2 source ↗

Find the volume inside x2+y2=1 and x2+z2=1⁠.

Answer

16/3

15.2.17 §15.2 source ↗

Find the volume under z=r above r=3+cos⁡θ⁠.

Answer

21π

15.2.19 §15.2 source ↗

Consider the integral ∫∫D⁡1x2+y2dA⁠, where D is the unit disk centered at the origin. (This is the same shape described in a different way in exercise 13 in section 9.7.)

a. Why might this integral be considered improper?

b. Calculate the value of the integral of the same function 1/x2+y2 over the annulus with outer radius 1 and inner radius δ⁠.

c. Obtain a value for the integral on the whole disk by letting δ approach 0.

Answer

2π

15.3.1 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the square [0,1]×[0,1] and has density function xy⁠.

Answer

x‾=y‾=2/3

15.3.2 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the triangle 0≤x≤1⁠, 0≤y≤x⁠, and has density function xy⁠.

Answer

x‾=4/5⁠, y‾=8/15

15.3.3 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the upper unit semicircle centered at (0,0) and has density function y⁠.

Answer

x‾=0⁠, y‾=3π/16

15.3.4 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the upper unit semicircle centered at (0,0) and has density function x2⁠.

Answer

x‾=0⁠, y‾=16/(15π)

15.3.5 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the triangle formed by x=2⁠, y=x⁠, and y=2x and has density function 2x⁠.

Answer

x‾=3/2⁠, y‾=9/4

15.3.6 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the triangle formed by x=0⁠, y=x⁠, and 2x+y=6 and has density function x2⁠.

Answer

x‾=6/5⁠, y‾=12/5

15.3.7 §15.3 source ↗

Find the center of mass of a two-dimensional plate that occupies the region enclosed by the parabolas x=y2⁠, y=x2 and has density function x⁠.

Answer

x‾=14/27⁠, y‾=28/55

15.3.8 §15.3 source ↗

Find the centroid of the area in the first quadrant bounded by x2−8y+4=0⁠, x2=4y⁠, and x=0⁠. (Recall that the centroid is the center of mass when the density is 1 everywhere.)

Answer

(3/4,2/5)

15.3.9 §15.3 source ↗

Find the centroid of one loop (say the loop along the x⁠-axis) of the three-leaf rose r=cos⁡(3θ)⁠. (Recall that the centroid is the center of mass when the density is 1 everywhere, and that the mass in this case is the same as the area, which was the subject of exercise 11 in section 15.2.) The computations of the integrals for the moments Mx and My are elementary but quite long; Sage can help.

Answer

(81380π,0)

15.3.10 §15.3 source ↗

Find the center of mass of a two dimensional object that occupies the region 0≤x≤π⁠, 0≤y≤sin⁡x⁠, with density σ=1⁠.

Answer

x‾=π/2⁠, y‾=π/8

15.3.11 §15.3 source ↗

A two-dimensional object has shape given by r=1+cos⁡θ and density σ(r,θ)=2+cos⁡θ⁠. Set up the three integrals required to compute the center of mass.

Answer

M= ∫02π ∫01+cos⁡θ(2+ cos⁡θ)rdrdθ⁠,

Mx= ∫02π ∫01+cos⁡θsin⁡θ(2+ cos⁡θ)r2drdθ⁠,

My= ∫02π ∫01+cos⁡θcos⁡θ(2+ cos⁡θ)r2drdθ⁠.

15.3.12 §15.3 source ↗

A two-dimensional object has shape given by r=cos⁡θ and density σ(r,θ)=r+1⁠. Set up the three integrals required to compute the center of mass.

Answer

M= ∫−π/2π/2 ∫0cos⁡θ(r+ 1)rdrdθ⁠,

Mx= ∫−π/2π/2 ∫0cos⁡θsin⁡θ(r+ 1)r2drdθ⁠,

My= ∫−π/2π/2 ∫0cos⁡θcos⁡θ(r+ 1)r2drdθ⁠.

15.3.13 §15.3 source ↗

A two-dimensional object sits inside r=1+cos⁡θ and outside r=cos⁡θ⁠, and has density 1 everywhere. Set up the integrals required to compute the center of mass.

Answer

M= ∫−π/2π/2 ∫cos⁡θ1+cos⁡θrdrdθ+ ∫π/23π/2∫01+cos⁡θrdrdθ⁠,

Mx= ∫−π/2π/2 ∫cos⁡θ1+cos⁡θr2sin⁡θdrdθ+ ∫π/23π/2 ∫01+cos⁡θr2sin⁡θdrdθ⁠,

My= ∫−π/2π/2 ∫cos⁡θ1+cos⁡θr2cos⁡θdrdθ+ ∫π/23π/2 ∫01+cos⁡θr2cos⁡θdrdθ⁠.

15.4.1 §15.4 source ↗

Find the area of the surface of a right circular cone of height h and base radius a⁠.

Answer

πah2+a2

15.4.2 §15.4 source ↗

Find the area of the portion of the plane z=mx inside the cylinder x2+y2=a2⁠.

Answer

πa2m2+1

15.4.3 §15.4 source ↗

Find the area of the portion of the plane x+y+z=1 in the first octant.

Answer

3/2

15.4.4 §15.4 source ↗

Find the area of the upper half of the cone x2+y2=z2 inside the cylinder x2+y2−2x=0⁠.

Answer

π2

15.4.5 §15.4 source ↗

Find the area of the upper half of the cone x2+y2=z2 above the interior of one loop of r=cos⁡(2θ)⁠.

Answer

π2/8

15.4.6 §15.4 source ↗

Find the area of the upper hemisphere of x2+y2+z2=1 above the interior of one loop of r=cos⁡(2θ)⁠.

Answer

π/2−1

15.4.7 §15.4 source ↗

The plane ax+by+cz=d cuts a triangle in the first octant provided that a,b,c and d are all positive. Find the area of this triangle.

Answer

d2a2+b2+c22abc

15.4.8 §15.4 source ↗

Find the area of the portion of the cone x2+y2=3z2 lying above the xy plane and inside the cylinder x2+y2=4y⁠.

Answer

83π/3

15.5.1 §15.5 source ↗

Evaluate ∫01∫0x∫0x+y2x+y−1dzdydx⁠.

Answer

11/24

15.5.2 §15.5 source ↗

Evaluate ∫02∫−1x2∫1yxyzdzdydx⁠.

Answer

623/60

15.5.3 §15.5 source ↗

Evaluate ∫01 ∫0x ∫0ln⁡yex+y+zdzdydx⁠.

Answer

−3e2/4+2e−3/4

15.5.4 §15.5 source ↗

Evaluate ∫0π/2 ∫0sin⁡θ ∫0rcos⁡θr2dzdrdθ⁠.

Answer

1/20

15.5.5 §15.5 source ↗

Evaluate ∫0π ∫0sin⁡θ ∫0rsin⁡θrcos2⁡θdzdrdθ⁠.

Answer

π/48

15.5.6 §15.5 source ↗

Evaluate ∫01∫0y2∫0x+yxdzdxdy⁠.

Answer

11/84

15.5.7 §15.5 source ↗

Evaluate ∫12 ∫yy2 ∫0ln⁡(y+z)exdxdzdy⁠.

Answer

151/60

15.5.8 §15.5 source ↗

Compute ∫0π∫0π/2∫01zsin⁡x+ zcos⁡ydzdydx⁠.

Answer

π

15.5.10 §15.5 source ↗

Compute ∫∫∫x+y+zdV over the region x2+y2+z2≤1 in the first octant.

Answer

3π16

15.5.11 §15.5 source ↗

Find the mass of a cube with edge length 2 and density equal to the square of the distance from one corner.

Answer

32

15.5.12 §15.5 source ↗

Find the mass of a cube with edge length 2 and density equal to the square of the distance from one edge.

Answer

64/3

15.5.13 §15.5 source ↗

An object occupies the volume of the upper hemisphere of x2+y2+z2=4 and has density z at (x,y,z)⁠. Find the center of mass.

Answer

x‾=y‾=0⁠, z‾=16/15

15.5.14 §15.5 source ↗

An object occupies the volume of the pyramid with corners at (1,1,0)⁠, (1,−1,0)⁠, (−1,−1,0)⁠, (−1,1,0)⁠, and (0,0,2) and has density x2+y2 at (x,y,z)⁠. Find the center of mass.

Answer

x‾=y‾=0⁠, z‾=1/3

15.6.1 §15.6 source ↗

Evaluate ∫01 ∫0x ∫0x2+y2(x2+y2)3/2x2+y2+z2dzdydx⁠.

Answer

π/12

15.6.2 §15.6 source ↗

Evaluate ∫−11 ∫01−x2 ∫x2+y22−x2−y2x2+y2+z2dzdydx⁠.

Answer

π(1−2/2)

15.6.3 §15.6 source ↗

Evaluate ∫∫∫x2dV over the interior of the cylinder x2+y2=1 between z=0 and z=5⁠.

Answer

5π/4

15.6.4 §15.6 source ↗

Evaluate ∫∫∫xydV over the interior of the cylinder x2+y2=1 between z=0 and z=5⁠.

Answer

0

15.6.5 §15.6 source ↗

Evaluate ∫∫∫zdV over the region above the x⁠-⁠y plane, inside x2+y2−2x=0 and under x2+y2+z2=4⁠.

Answer

5π/4

15.6.6 §15.6 source ↗

Evaluate ∫∫∫yzdV over the region in the first octant, inside x2+y2−2x=0 and under x2+y2+z2=4⁠.

Answer

4/5

15.6.7 §15.6 source ↗

Evaluate ∫∫∫x2+y2dV over the interior of x2+y2+z2=4⁠.

Answer

256π/15

15.6.8 §15.6 source ↗

Evaluate ∫∫∫x2+y2dV over the interior of x2+y2+z2=4⁠.

Answer

4π2

15.6.9 §15.6 source ↗

Compute ∫∫∫x+y+zdV over the region inside x2+y2+z2=1 in the first octant.

Answer

3π16

15.6.10 §15.6 source ↗

Find the mass of a right circular cone of height h and base radius a if the density k is proportional to the distance from the base.

Answer

πkh2a2/12

15.6.11 §15.6 source ↗

Find the mass of a right circular cone of height h and base radius a if the density k is proportional to the distance from its axis of symmetry.

Answer

πkha3/6

15.6.12 §15.6 source ↗

An object occupies the region inside the unit sphere at the origin, and has density equal to the distance from the x⁠-axis. Find the mass.

Answer

π2/4

15.6.13 §15.6 source ↗

An object occupies the region inside the unit sphere at the origin, and has density equal to the square of the distance from the origin. Find the mass.

Answer

4π/5

15.6.14 §15.6 source ↗

An object occupies the region between the unit sphere at the origin and a sphere of radius 2 with center at the origin, and has density equal to the distance from the origin. Find the mass.

Answer

15π

15.6.15 §15.6 source ↗

An object occupies the region in the first octant bounded by the cones ϕ=π/4 and ϕ=arctan⁡2⁠, and the sphere ρ=6⁠, and has density k proportional to the distance from the origin. Find the mass.

Answer

9kπ(52−25)/20

15.7.1 §15.7 source ↗

Complete example 15.7.1 by converting to polar coordinates and evaluating the integral.

Answer

4π3/3

15.7.2 §15.7 source ↗

Evaluate ∫∫⁡xydxdy over the square with corners (0,0)⁠, (1,1)⁠, (2,0)⁠, and (1,−1) in two ways: directly, and using x=(u+v)/2⁠, y=(u−v)/2⁠.

Answer

0

15.7.3 §15.7 source ↗

Evaluate ∫∫⁡x2+y2dxdy over the square with corners (−1,0)⁠, (0,1)⁠, (1,0)⁠, and (0,−1) in two ways: directly, and using x=(u+v)/2⁠, y=(u−v)/2⁠.

Answer

2/3

15.7.4 §15.7 source ↗

Evaluate ∫∫⁡(x+y)ex−ydxdy over the triangle with corners (0,0)⁠, (−1,1)⁠, and (1,1) in two ways: directly, and using x=(u+v)/2⁠, y=(u−v)/2⁠.

Answer

e2−12e2

15.7.5 §15.7 source ↗

Evaluate ∫∫⁡y(x−y)dxdy over the parallelogram with corners (0,0)⁠, (3,3)⁠, (7,3)⁠, and (4,0) in two ways: directly, and using x=u+v⁠, y=u⁠.

Answer

36

15.7.6 §15.7 source ↗

Evaluate ∫∫⁡x2+y2dxdy over the triangle with corners (0,0)⁠, (4,4)⁠, and (4,0) using x=u⁠, y=uv⁠.

Answer

32(2+ln⁡(1+2))/3

15.7.7 §15.7 source ↗

Evaluate ∫∫⁡ysin⁡(xy)dxdy over the region bounded by xy=1⁠, xy=4⁠, y=1⁠, and y=4 using x=u/v⁠, y=v⁠.

Answer

3cos⁡(1)−3cos⁡(4)

15.7.8 §15.7 source ↗

Evaluate ∫∫⁡sin⁡(9x2+4y2)dA, over the region in the first quadrant bounded by the ellipse 9x2+4y2=1⁠.

Answer

π(1−cos⁡(1))/24

15.7.9 §15.7 source ↗

Compute the Jacobian for the substitutions x=ρsin⁡ϕcos⁡θ⁠, y=ρsin⁡ϕsin⁡θ⁠, z=ρcos⁡ϕ⁠.

Answer

ρ2sin⁡ϕ

15.7.10 §15.7 source ↗

Evaluate ∫∫∫E⁡dV where E is the solid enclosed by the ellipsoid x2a2+y2b2+z2c2=1, using the transformation x=au⁠, y=bv⁠, and z=cw⁠.

Answer

(4/3)πabc

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Exercises and answers are adapted from Calculus: Early Transcendentals by David Guichard and friends, which is free to read and download, and are used under the CC BY-NC-SA 4.0 licence. They are taken from the book’s online edition and set for the web, so they may differ slightly from the printed page. This adaptation is released under the same licence and is neither affiliated with nor endorsed by David Guichard or Whitman College. The book was first written by David Guichard. Its chapters 1–9 modify and expand notes by Neal Koblitz of the University of Washington; it includes exercises and examples from H. Jerome Keisler’s Elementary Calculus: An Approach Using Infinitesimals, from which its chapter on differential equations is largely derived, and some exercises from the OpenStax Calculus books; and Albert Schueller, Barry Balof and Mike Wills contributed additional material.