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Thomas Calculus 13th [Solutions]

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Chapter 3 Practice Exercises 201<br />

28.<br />

2 2 3<br />

y x sin ( x )<br />

dy<br />

dx<br />

2 3 3 2 2 3 3<br />

x (2sin ( x )) (cos ( x ))(3 x ) sin ( x )( 2 x )<br />

3 3 3 2 3<br />

6sin ( x ) cos ( x ) 2x sin ( x )<br />

29.<br />

4t<br />

t 1<br />

2<br />

ds<br />

dt<br />

4t<br />

3 ( t 1)(4) (4 t )(1)<br />

t 1 ( t 1)<br />

s 2<br />

2<br />

2<br />

4t<br />

3 4 ( t 1)<br />

t 1 2 3<br />

( t 1) 8t<br />

30. s 1<br />

3<br />

15(15t<br />

1)<br />

1 3<br />

15 (15 1) ds<br />

dt<br />

1<br />

4 3<br />

15 (15 t 1)<br />

t ( 3)(15 t 1) (15)<br />

4<br />

31.<br />

y<br />

x<br />

x 1<br />

2<br />

dy<br />

dx<br />

2<br />

1<br />

2 x<br />

( x 1) x (1)<br />

x<br />

x 1 2<br />

( x 1)<br />

( x 1) 2x 1 x<br />

( x 1) ( x 1)<br />

3 3<br />

32.<br />

y<br />

2 x<br />

2 x 1<br />

2<br />

dy<br />

dx<br />

2<br />

1<br />

x<br />

1<br />

x<br />

x<br />

2<br />

(2 x 1) 2<br />

2 x<br />

2 x 1 (2 x 1)<br />

4 x<br />

1<br />

x 4<br />

3 3<br />

(2 x 1) (2 x 1)<br />

33.<br />

1/2<br />

dy<br />

dx<br />

y<br />

2<br />

x x 1 1<br />

1 1 1<br />

2<br />

2<br />

x<br />

x<br />

1/2<br />

2 1 1<br />

x x<br />

2<br />

2x<br />

1<br />

1<br />

x<br />

1/2 1/2 dy<br />

34. y 4x x x 4 x( x x )<br />

1 1/2 1/2 1/2 1/2 1/2<br />

4 x ( x x ) 1 1 x ( x x ) (4)<br />

dx 2<br />

2<br />

1 2 1<br />

1 2 6x<br />

5 x<br />

( x x) 2x 1 4( x x) ( x x) (2x x 4x 4 x)<br />

2 x x x<br />

35.<br />

2<br />

sin<br />

cos 1<br />

dr<br />

d<br />

sin (cos 1)(cos ) (sin )( sin )<br />

cos 1 (cos 1)<br />

2sin<br />

(cos<br />

2<br />

1)<br />

r 2<br />

2<br />

(2sin )(1 cos )<br />

3<br />

(cos 1)<br />

2<br />

2 2<br />

sin cos cos sin<br />

cos 1 2<br />

(cos 1)<br />

36.<br />

sin 1<br />

1 cos<br />

2<br />

dr<br />

d<br />

sin 1 (1 cos )(cos ) (sin 1)(sin )<br />

1 cos (1 cos )<br />

r 2 2<br />

3<br />

2(sin 1)(cos sin 1)<br />

3<br />

(1 cos )<br />

2(sin 1) 2 2<br />

(cos cos sin sin )<br />

(1 cos )<br />

37. y (2x 1) 2x<br />

1<br />

3/2<br />

(2x<br />

1)<br />

dy<br />

dx<br />

3 1/2<br />

(2 1) (2) 3 2 1<br />

2 x<br />

x<br />

38.<br />

1/4 1/5<br />

y 20(3x 4) (3x<br />

4)<br />

1/20<br />

20(3 4)<br />

dy<br />

dx<br />

1<br />

19/20 3<br />

20 (3 x 4)<br />

x 20 (3x<br />

4) (3)<br />

19/20<br />

39.<br />

2 3/2<br />

y 3(5x sin 2 x)<br />

dy<br />

dx<br />

3 2 5/2<br />

9(5x<br />

cos 2 x)<br />

3 (5x sin 2 x) [10 x (cos 2 x)(2)]<br />

2<br />

2<br />

5/2<br />

5x<br />

sin 2x<br />

40.<br />

y<br />

3 1/3<br />

(3 cos 3 x)<br />

dy<br />

dx<br />

1 3 4/3 2<br />

(3 cos 3 ) (3cos 3 )( sin 3 )(3)<br />

3 x x x 2<br />

3cos 3xsin 3x<br />

3 4/3<br />

(3 cos 3 x)<br />

41.<br />

x/5 dy 1 x/5 x/5<br />

y 10 e (10) e 2e<br />

dx 5<br />

42.<br />

2x dy<br />

2x 2x<br />

y 2e 2 2 e 2e<br />

dx<br />

Copyright<br />

2014 Pearson Education, Inc.

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