Chapter 3

Chapter 3

Checkpoint

3.1

∫ ​ x e 2 x d x = 1 2 x e 2 x − 1 4 e 2 x + C ∫ ​ x e 2 x d x = 1 2 x e 2 x − 1 4 e 2 x + C

3.2

1 2 x 2 ln x − 1 4 x 2 + C 1 2 x 2 ln x − 1 4 x 2 + C

3.3

− x 2 cos x + 2 x sin x + 2 cos x + C − x 2 cos x + 2 x sin x + 2 cos x + C

3.4

π 2 − 1 π 2 − 1

3.5

1 5 sin 5 x + C 1 5 sin 5 x + C

3.6

1 3 sin 3 x − 1 5 sin 5 x + C 1 3 sin 3 x − 1 5 sin 5 x + C

3.7

1 2 x + 1 4 sin ( 2 x ) + C 1 2 x + 1 4 sin ( 2 x ) + C

3.8

sin x − 1 3 sin 3 x + C sin x − 1 3 sin 3 x + C

3.9

1 2 x + 1 12 sin ( 6 x ) + C 1 2 x + 1 12 sin ( 6 x ) + C

3.10

1 2 sin x + 1 22 sin ( 11 x ) + C 1 2 sin x + 1 22 sin ( 11 x ) + C

3.11

1 6 tan 6 x + C 1 6 tan 6 x + C

3.12

1 9 sec 9 x − 1 7 sec 7 x + C 1 9 sec 9 x − 1 7 sec 7 x + C

3.13

∫ sec 5 x d x = 1 4 sec 3 x tan x + 3 4 ∫ sec 3 x ∫ sec 5 x d x = 1 4 sec 3 x tan x + 3 4 ∫ sec 3 x

3.14

∫ ​ 125 sin 3 θ d θ ∫ ​ 125 sin 3 θ d θ

3.15

∫ ​ 32 tan 3 θ sec 3 θ d θ ∫ ​ 32 tan 3 θ sec 3 θ d θ

3.16

ln | x 2 + x 2 − 4 2 | + C ln | x 2 + x 2 − 4 2 | + C

3.17

x − 5 ln | x + 2 | + C x − 5 ln | x + 2 | + C

3.18

2 5 ln | x + 3 | + 3 5 ln | x − 2 | + C 2 5 ln | x + 3 | + 3 5 ln | x − 2 | + C

3.19

x + 2 ( x + 3 ) 3 ( x − 4 ) 2 = A x + 3 + B ( x + 3 ) 2 + C ( x + 3 ) 3 + D ( x − 4 ) + E ( x − 4 ) 2 x + 2 ( x + 3 ) 3 ( x − 4 ) 2 = A x + 3 + B ( x + 3 ) 2 + C ( x + 3 ) 3 + D ( x − 4 ) + E ( x − 4 ) 2

3.20

x 2 + 3 x + 1 ( x + 2 ) ( x − 3 ) 2 ( x 2 + 4 ) 2 = A x + 2 + B x − 3 + C ( x − 3 ) 2 + D x + E x 2 + 4 + F x + G ( x 2 + 4 ) 2 x 2 + 3 x + 1 ( x + 2 ) ( x − 3 ) 2 ( x 2 + 4 ) 2 = A x + 2 + B x − 3 + C ( x − 3 ) 2 + D x + E x 2 + 4 + F x + G ( x 2 + 4 ) 2

3.21

Possible solutions include sinh−1(x2)+Csinh−1(x2)+C and ln|x2+4+x|+C.ln|x2+4+x|+C.

3.22

24 35 24 35

3.23

17 24 17 24

3.24

0.0074, 1.1%

3.25

1 192 1 192

3.26

25 36 25 36

3.27

e3,e3, converges

3.28

+∞,+∞, diverges

3.29

Since ∫e+∞1xdx=+∞,∫e+∞1xdx=+∞, ∫e+∞lnxxdx∫e+∞lnxxdx diverges.

Section 3.1 Exercises

1.

u = x 3 u = x 3

3.

u = y 3 u = y 3

5.

u = sin ( 2 x ) u = sin ( 2 x )

7.

− x + x ln x + C − x + x ln x + C

9.

x tan −1 x − 1 2 ln ( 1 + x 2 ) + C x tan −1 x − 1 2 ln ( 1 + x 2 ) + C

11.

− 1 2 x cos ( 2 x ) + 1 4 sin ( 2 x ) + C − 1 2 x cos ( 2 x ) + 1 4 sin ( 2 x ) + C

13.

e − x ( −1 − x ) + C e − x ( −1 − x ) + C

15.

2 x cos x + ( −2 + x 2 ) sin x + C 2 x cos x + ( −2 + x 2 ) sin x + C

17.

1 2 ( 1 + 2 x ) ( −1 + ln ( 1 + 2 x ) ) + C 1 2 ( 1 + 2 x ) ( −1 + ln ( 1 + 2 x ) ) + C

19.

1 2 e x ( − cos x + sin x ) + C 1 2 e x ( − cos x + sin x ) + C

21.

− e − x 2 2 + C − e − x 2 2 + C

23.

− 1 2 x cos [ ln ( 2 x ) ] + 1 2 x sin [ ln ( 2 x ) ] + C − 1 2 x cos [ ln ( 2 x ) ] + 1 2 x sin [ ln ( 2 x ) ] + C

25.

2 x − 2 x ln x + x ( ln x ) 2 + C 2 x − 2 x ln x + x ( ln x ) 2 + C

27.

( − x 3 9 + 1 3 x 3 ln x ) + C ( − x 3 9 + 1 3 x 3 ln x ) + C

29.

− 1 2 1 − 4 x 2 + x cos −1 ( 2 x ) + C − 1 2 1 − 4 x 2 + x cos −1 ( 2 x ) + C

31.

− ( −2 + x 2 ) cos x + 2 x sin x + C − ( −2 + x 2 ) cos x + 2 x sin x + C

33.

− x ( −6 + x 2 ) cos x + 3 ( −2 + x 2 ) sin x + C − x ( −6 + x 2 ) cos x + 3 ( −2 + x 2 ) sin x + C

35.

1 2 x ( − 1 − 1 x 2 + x · sec −1 x ) + C 1 2 x ( − 1 − 1 x 2 + x · sec −1 x ) + C

37.

− cosh x + x sinh x + C − cosh x + x sinh x + C

39.

1 4 − 3 4 e 2 1 4 − 3 4 e 2

41.

2

43.

2 π 2 π

45.

−2 + π −2 + π

47.

− sin ( x ) + ln [ sin ( x ) ] sin x + C − sin ( x ) + ln [ sin ( x ) ] sin x + C

49.

Answers vary

51.

a. 25(1+x)(−3+2x)3/2+C25(1+x)(−3+2x)3/2+C b. 25(1+x)(−3+2x)3/2+C25(1+x)(−3+2x)3/2+C

53.

Do not use integration by parts. Choose u to be lnx,lnx, and the integral is of the form ∫u2du.∫u2du.

55.

Do not use integration by parts. Let u=x2−3,u=x2−3, and the integral can be put into the form ∫eudu.∫eudu.

57.

Do not use integration by parts. Choose u to be u=3x3+2u=3x3+2 and the integral can be put into the form ∫sin(u)du.∫sin(u)du.

59.

The area under graph is 0.39535.

This figure is the graph of y=e^-x sin(pi*x). The curve begins in the third quadrant at x=0.5, increases through the origin, reaches a high point between 0.5 and 0.75, then decreases, passing through x=1.
61.

2 π e 2 π e

63.

2.05

65.

12 π 12 π

67.

8 π 2 8 π 2

Section 3.2 Exercises

69.

cos 2 x cos 2 x

71.

1 − cos ( 2 x ) 2 1 − cos ( 2 x ) 2

73.

sin 4 x 4 + C sin 4 x 4 + C

75.

1 12 tan 6 ( 2 x ) + C 1 12 tan 6 ( 2 x ) + C

77.

( x 2 ) x 2 + C 1   or sec 2 x 2 + C 2 ( x 2 ) x 2 + C 1   or sec 2 x 2 + C 2

79.

– cos x + 1 3 cos 3 x + C – cos x + 1 3 cos 3 x + C

81.

−12cos2x+C−12cos2x+C or 12sin2x+C12sin2x+C

83.

– 1 3 cos 3 x + 2 5 cos 5 x – 1 7 cos 7 x + C – 1 3 cos 3 x + 2 5 cos 5 x – 1 7 cos 7 x + C

85.

2 3 ( sin x ) 3 2 + C 2 3 ( sin x ) 3 2 + C

87.

sec x + C sec x + C

89.

1 2 sec x tan x − 1 2 ln ( sec x + tan x ) + C 1 2 sec x tan x − 1 2 ln ( sec x + tan x ) + C

91.

2tanx3+13sec(x)2tanx2tanx3+13sec(x)2tanx =tanx+tan3x3+C=tanx+tan3x3+C

93.

− ln | cot x + csc x | + C − ln | cot x + csc x | + C

95.

sin 3 ( a x ) 3 a + C sin 3 ( a x ) 3 a + C

97.

π 2 π 2

99.

x 2 + 1 12 sin ( 6 x ) + C x 2 + 1 12 sin ( 6 x ) + C

101.

x+Cx+C

103.

0

105.

0

107.

0

109.

Approximately 0.239

111.

2 2

113.

1.0

115.

0

117.

3 θ 8 − 1 4 π sin ( 2 π θ ) + 1 32 π sin ( 4 π θ ) + C = f ( x ) 3 θ 8 − 1 4 π sin ( 2 π θ ) + 1 32 π sin ( 4 π θ ) + C = f ( x )

119.

ln ( 3 ) ln ( 3 )

121.

∫ − π π sin ( 2 x ) cos ( 3 x ) d x = 0 ∫ − π π sin ( 2 x ) cos ( 3 x ) d x = 0

123.

tan ( x ) x ( 8 tan x 21 + 2 7 sec x 2 tan x ) + C = f ( x ) tan ( x ) x ( 8 tan x 21 + 2 7 sec x 2 tan x ) + C = f ( x )

125.

The second integral is more difficult because the first integral is simply a u-substitution type.

Section 3.3 Exercises

127.

9 tan 2 θ 9 tan 2 θ

129.

a 2 cosh 2 θ a 2 cosh 2 θ

131.

4 ( x − 1 2 ) 2 4 ( x − 1 2 ) 2

133.

− ( x + 1 ) 2 + 5 − ( x + 1 ) 2 + 5

135.

ln | x 2 − a 2 + x a | + C ln | x 2 − a 2 + x a | + C

137.

1 3 ln | 9 x 2 + 1 + 3 x | + C 1 3 ln | 9 x 2 + 1 + 3 x | + C

139.

− 1 − x 2 x + C − 1 − x 2 x + C

141.

9 [ x x 2 + 9 18 + 1 2 l n | x 2 + 9 3 + x 3 | ] + C 9 [ x x 2 + 9 18 + 1 2 l n | x 2 + 9 3 + x 3 | ] + C

143.

− 1 3 9 − θ 2 ( 18 + θ 2 ) + C − 1 3 9 − θ 2 ( 18 + θ 2 ) + C

145.

( −1 + x 2 ) ( 2 + 3 x 2 ) x 6 − x 8 15 x 3 + C ( −1 + x 2 ) ( 2 + 3 x 2 ) x 6 − x 8 15 x 3 + C

147.

− x 9 −9 + x 2 + C − x 9 −9 + x 2 + C

149.

1 2 ( ln | x + x 2 − 1 | + x x 2 − 1 ) + C 1 2 ( ln | x + x 2 − 1 | + x x 2 − 1 ) + C

151.

− 1 + x 2 x + C − 1 + x 2 x + C

153.

1 8 ( x ( 5 − 2 x 2 ) 1 − x 2 + 3 arcsin x ) + C 1 8 ( x ( 5 − 2 x 2 ) 1 − x 2 + 3 arcsin x ) + C

155.

ln x − ln | 1 + 1 − x 2 | + C ln x − ln | 1 + 1 − x 2 | + C

157.

− −1 + x 2 x + ln | x + −1 + x 2 | + C − −1 + x 2 x + ln | x + −1 + x 2 | + C

159.

− 1 + x 2 x + arcsinh x + C − 1 + x 2 x + arcsinh x + C

161.

− 1 1 + x + C − 1 1 + x + C

163.

arcsin x - 5 5 + C arcsin x - 5 5 + C

165.

9π2;9π2; area of a semicircle with radius 3

167.

arcsin(x)+Carcsin(x)+C is the common answer.

169.

12ln(1+x2)+C12ln(1+x2)+C is the result using either method.

171.

Use trigonometric substitution. Let x=sec(θ).x=sec(θ).

173.

4.367

175.

π 2 8 + π 4 π 2 8 + π 4

177.

y = 1 16 ln | x + 8 x − 8 | + 3 y = 1 16 ln | x + 8 x − 8 | + 3

179.

24.6 m3

181.

2 π 3 2 π 3

Section 3.4 Exercises

183.

− 2 x + 1 + 5 2 ( x + 2 ) + 1 2 x − 2 x + 1 + 5 2 ( x + 2 ) + 1 2 x

185.

1 x 2 + 3 x 1 x 2 + 3 x

187.

2 x 2 + 4 x + 8 + 16 x − 2 2 x 2 + 4 x + 8 + 16 x − 2

189.

− 1 x 2 − 1 x + 1 x − 1 − 1 x 2 − 1 x + 1 x − 1

191.

− 1 2 ( x − 2 ) + 1 2 ( x − 1 ) − 1 6 x + 1 6 ( x − 3 ) − 1 2 ( x − 2 ) + 1 2 ( x − 1 ) − 1 6 x + 1 6 ( x − 3 )

193.

1 x − 1 + 2 x + 1 x 2 + x + 1 1 x − 1 + 2 x + 1 x 2 + x + 1

195.

2 x + 1 + x x 2 + 4 − 1 ( x 2 + 4 ) 2 2 x + 1 + x x 2 + 4 − 1 ( x 2 + 4 ) 2

197.

ln | x − 2 | + 2 ln | x + 4 | + C ln | x − 2 | + 2 ln | x + 4 | + C

199.

1 2 ln | 4 − x 2 | + C 1 2 ln | 4 − x 2 | + C

201.

2 ( x + 1 3 arctan ( 1 + x 3 ) ) + C 2 ( x + 1 3 arctan ( 1 + x 3 ) ) + C

203.

2 ln | x | − 3 ln | 1 + x | + C 2 ln | x | − 3 ln | 1 + x | + C

205.

1 16 ( − 4 −2 + x − ln | −2 + x | + ln | 2 + x | ) + C 1 16 ( − 4 −2 + x − ln | −2 + x | + ln | 2 + x | ) + C

207.

1 30 ( −2 5 arctan [ 1 + x 5 ] + 2 ln | −4 + x | − ln | 6 + 2 x + x 2 | ) + C 1 30 ( −2 5 arctan [ 1 + x 5 ] + 2 ln | −4 + x | − ln | 6 + 2 x + x 2 | ) + C

209.

− 3 x + 4 ln | x + 2 | + x + C − 3 x + 4 ln | x + 2 | + x + C

211.

− ln | 3 − x | + 1 2 ln | x 2 + 4 | + C − ln | 3 − x | + 1 2 ln | x 2 + 4 | + C

213.

ln | x − 2 | − 1 2 ln | x 2 + 2 x + 2 | + C ln | x − 2 | − 1 2 ln | x 2 + 2 x + 2 | + C

215.

− x + ln | 1 − e x | + C − x + ln | 1 − e x | + C

217.

1 5 ln | cos x + 3 cos x − 2 | + C 1 5 ln | cos x + 3 cos x − 2 | + C

219.

1 2 − 2 e 2 t + C 1 2 − 2 e 2 t + C

221.

2 1 + x − 2 ln | 1 + 1 + x | + C 2 1 + x − 2 ln | 1 + 1 + x | + C

223.

ln | sin x 1 − sin x | + C ln | sin x 1 − sin x | + C

225.

3 4 3 4

227.

x − ln ( 1 + e x ) + C x − ln ( 1 + e x ) + C

229.

6 x 1 / 6 − 3 x 1 / 3 + 2 x − 6 ln ( 1 + x 1 / 6 ) + C 6 x 1 / 6 − 3 x 1 / 3 + 2 x − 6 ln ( 1 + x 1 / 6 ) + C

231.

4 3 π arctanh [ 1 3 ] = 1 3 π ln 4 4 3 π arctanh [ 1 3 ] = 1 3 π ln 4

233.

x = − ln | t − 3 | + ln | t − 4 | + ln 2 x = − ln | t − 3 | + ln | t − 4 | + ln 2

235.

x = ln | t − 1 | − 2 arctan ( 2 t ) − 1 2 ln ( t 2 + 1 2 ) + 2 arctan ( 2 2 ) + 1 2 ln 4.5 x = ln | t − 1 | − 2 arctan ( 2 t ) − 1 2 ln ( t 2 + 1 2 ) + 2 arctan ( 2 2 ) + 1 2 ln 4.5

237.

2 5 π ln 28 13 2 5 π ln 28 13

239.

arctan [ −1 + 2 x 3 ] 3 + 1 3 ln | 1 + x | − 1 6 ln | 1 − x + x 2 | + C arctan [ −1 + 2 x 3 ] 3 + 1 3 ln | 1 + x | − 1 6 ln | 1 − x + x 2 | + C

241.

2.0 in.2

243.

3 ( −8 + x ) 1 / 3 3 ( −8 + x ) 1 / 3
−2 3 arctan [ −1 + ( −8 + x ) 1 / 3 3 ] −2 3 arctan [ −1 + ( −8 + x ) 1 / 3 3 ]
−2 ln [ 2 + ( −8 + x ) 1 / 3 ] −2 ln [ 2 + ( −8 + x ) 1 / 3 ]
+ ln [ 4 − 2 ( −8 + x ) 1 / 3 + ( −8 + x ) 2 / 3 ] + C + ln [ 4 − 2 ( −8 + x ) 1 / 3 + ( −8 + x ) 2 / 3 ] + C

Section 3.5 Exercises

245.

1 2 ln | x 2 + 2 x + 2 | + 2 arctan ( x + 1 ) + C 1 2 ln | x 2 + 2 x + 2 | + 2 arctan ( x + 1 ) + C

247.

cosh −1 ( x + 3 3 ) + C cosh −1 ( x + 3 3 ) + C

249.

2 x 2 − 1 ln 2 + C 2 x 2 − 1 ln 2 + C

251.

arcsin ( y 2 ) + C arcsin ( y 2 ) + C

253.

− 1 2 csc ( 2 w ) + C − 1 2 csc ( 2 w ) + C

255.

9 − 6 2 9 − 6 2

257.

2 − π 2 2 − π 2

259.

1 12 tan 4 ( 3 x ) − 1 6 tan 2 ( 3 x ) + 1 3 ln | sec ( 3 x ) | + C 1 12 tan 4 ( 3 x ) − 1 6 tan 2 ( 3 x ) + 1 3 ln | sec ( 3 x ) | + C

261.

2 cot ( w 2 ) − 2 csc ( w 2 ) + w + C 2 cot ( w 2 ) − 2 csc ( w 2 ) + w + C

263.

1 5 ln | 2 ( 5 + 4 sin t − 3 cos t ) 4 cos t + 3 sin t | 1 5 ln | 2 ( 5 + 4 sin t − 3 cos t ) 4 cos t + 3 sin t |

265.

6 x 1 / 6 − 3 x 1 / 3 + 2 x − 6 ln [ 1 + x 1 / 6 ] + C 6 x 1 / 6 − 3 x 1 / 3 + 2 x − 6 ln [ 1 + x 1 / 6 ] + C

267.

− x 3 cos x + 3 x 2 sin x + 6 x cos x − 6 sin x + C − x 3 cos x + 3 x 2 sin x + 6 x cos x − 6 sin x + C

269.

1 2 ( x 2 + ln | 1 + e − x 2 | ) + C 1 2 ( x 2 + ln | 1 + e − x 2 | ) + C

271.

2 arctan ( x − 1 ) + C 2 arctan ( x − 1 ) + C

273.

0.5 = 1 2 0.5 = 1 2

275.

8.0

277.

1 3 arctan ( 1 3 ( x + 2 ) ) + C 1 3 arctan ( 1 3 ( x + 2 ) ) + C

279.

1 3 arctan ( x + 1 3 ) + C 1 3 arctan ( x + 1 3 ) + C

281.

ln ( e x + –4 + e 2 x ) + C ln ( e x + –4 + e 2 x ) + C

283.

ln x − 1 6 ln ( x 6 + 1 ) − arctan ( x 3 ) 3 x 3 + C ln x − 1 6 ln ( x 6 + 1 ) − arctan ( x 3 ) 3 x 3 + C

285.

ln | x + 16 + x 2 | + C ln | x + 16 + x 2 | + C

287.

− 1 4 cot ( 2 x ) + C − 1 4 cot ( 2 x ) + C

289.

1 2 arctan 10 1 2 arctan 10

291.

1276.14

293.

7.21

295.

5 − 2 + ln | 2 + 2 2 1 + 5 | 5 − 2 + ln | 2 + 2 2 1 + 5 |

297.

1 3 arctan ( 3 ) ≈ 0.416 1 3 arctan ( 3 ) ≈ 0.416

Section 3.6 Exercises

299.

0.696

301.

9.484

303.

0.5000

305.

T 4 = 18.75 T 4 = 18.75

307.

0.500

309.

1.129

311.

0.6577

313.

0.0213

315.

1.5629

317.

1.9133

319.

T(4) = 0.1088 T(4) = 0.1088

321.

1.0

323.

Approximate error is 0.000325.

325.

1 7938 1 7938

327.

81 25 , 000 81 25 , 000

329.

475

331.

174

333.

0.1544

335.

6.2807

337.

4.606

339.

3.41 ft

341.

T16=100.125;T16=100.125; absolute error = 0.125

343.

about 89,250 m2

345.

parabola

Section 3.7 Exercises

347.

divergent

349.

π 2 π 2

351.

2 e 2 e

353.

Converges

355.

Converges to 1/2.

357.

−4

359.

π π

361.

diverges

363.

diverges

365.

1.5

367.

diverges

369.

diverges

371.

diverges

373.

Both integrals diverge.

375.

diverges

377.

diverges

379.

π π

381.

0.0

383.

0.0

385.

6.0

387.

π 2 π 2

389.

8 ln ( 16 ) − 4 8 ln ( 16 ) − 4

391.

1.047 1.047

393.

−1 + 2 3 −1 + 2 3

395.

7.0

397.

5 π 2 5 π 2

399.

3 π 3 π

401.

1 s , s > 0 1 s , s > 0

403.

s s 2 + 4 , s > 0 s s 2 + 4 , s > 0

405.

Answers will vary.

407.

0.8775

Review Exercises

409.

False

411.

False

413.

− x 2 + 16 16 x + C − x 2 + 16 16 x + C

415.

1 10 ( 4 ln ( 2 − x ) + 5 ln ( x + 1 ) − 9 ln ( x + 3 ) ) + C 1 10 ( 4 ln ( 2 − x ) + 5 ln ( x + 1 ) − 9 ln ( x + 3 ) ) + C

417.

− 4 − sin 2 ( x ) sin ( x ) − x 2 + C − 4 − sin 2 ( x ) sin ( x ) − x 2 + C

419.

1 15 ( x 2 + 2 ) 3 / 2 ( 3 x 2 − 4 ) + C 1 15 ( x 2 + 2 ) 3 / 2 ( 3 x 2 − 4 ) + C

421.

1 16 ln ( x 2 + 2 x + 2 x 2 − 2 x + 2 ) − 1 8 tan −1 ( 1 − x ) + 1 8 tan −1 ( x + 1 ) + C 1 16 ln ( x 2 + 2 x + 2 x 2 − 2 x + 2 ) − 1 8 tan −1 ( 1 − x ) + 1 8 tan −1 ( x + 1 ) + C

423.

M 4 = 3.312 , T 4 = 3.354 , S 4 = 3.326 M 4 = 3.312 , T 4 = 3.354 , S 4 = 3.326

425.

M 4 = −0.982 , T 4 = −0.917 , S 4 = −0.952 M 4 = −0.982 , T 4 = −0.917 , S 4 = −0.952

427.

approximately 0.2194

431.

Answers may vary. Ex: 9.4059.405 km