
P1: JXR
MHDQ256-APP-B MHDQ256-Smith-v1.cls January 12, 2011 7:22
LT (Late Transcendental)
CONFIRMING PAGES
APPENDIX B
..
Answers to Odd-Numbered Exercises A-25
19.
15
7
≈ 2.143 miles east of first development
21. 1.2529 miles east of bridge; $1.964 million 23. y = 0.568
27. r =
2
3
r
0
, contracts 29. x = R 31. 2
× 2
33. printed region:
√
46
× 2
√
46
; overall: (
√
46 +2)
× (2
√
46 +4)
35. (a) 12.7 ft (c) 1.1 ft (d) (L
2/3
− a
2/3
)
3/2
37. 4 39. (a) 50
◦
(b) 45
◦
(c) 40
◦
41. max area is 2ab 43. A =
P
2
12
√
3
Exercises 3.7, page 237
1. (a) 1.22 ft/min (b) 0.61 ft/min
3. (a) 58.9 gal/min (b) halved
7. (a) −2.25 ft/s (b)
−3
8
rad/s
9. (a) 24
√
101 ≈ 241 mph (b) 242.7 mph
13. s
(20) = 1.47152 thousand dollars per year
15. −2 dollars per year 17. (a) −65 rad/s (b) 6 ft/s
19. (a) 1 ft/s (b) −1.5 ft/s
21. 2.088 when x = 20, 2.332 when x = 10
23. 1760 Hz/s;
1
8
second 25. (a) 0 (b)
60
√
2
ft
29. (a) 8 − x = 0.568 at t = 1.16
Exercises 3.8, page 245
1. 3x
2
+ 40x +90; 9590 vs. 9421
3. 3x
2
+ 42x +110; 34,310 vs. 33,990
5. x = 10; costs rise more sharply 7. x =
20,000 ≈ 141
9. x =
3
√
18
11. (a) C
(100) = 42, C(100) = 77; C(101) = 76.65 < C(100)
(c) min at x = 600;C
(600) = C(600) = 52
13. (a)
p
p − 30
(b) 15 < p < 30
15. (a)
2p −20
p − 20
(b)
40
3
< p < 20
19. (a) 2 (b) 8 21. r = cK 23. 0; same
25. −
5
7
c
5/7
p
−12/7
27. 4 −cos x; less dense at ends 29. 4; homogeneous
31. 2.5
33. f
(x) =
−816x
−1.4
4x
−0.4
+ 15
2
< 0
37. the critical number is 2c, representing a minimum
39. x =
cr
2
r
1
, y =
cr
1
r
2
Chapter 3 Review Exercises, page 247
1. 1 3. 2 +
1
12
(7.96 −8) ≈ 1.99666
5. 0.198437 7. f
(1) = 0
9. (a) x =−3, 1
(b) increase: x < −3, x > 1; decrease: −3 < x < 1
(c) local max at x =−3, local min at x = 1
(d) up: x > −1, down: x < −1 (e) x =−1
11. (a) x = 0, 3 (b) increase: x > 3; decrease: x < 3(x = 0)
(c) min at x = 3 (d) up: x < 0, x > 2; down: 0 < x < 2
(e) x = 0, x = 2
13. (a) x = 180 (b) 0 < x < 180; x < 0 and x > 180
(c) local maximum at x = 180
(d) f is concave up for x > 270; f is concave
down for x < 0 and 0 < x < 270
(e) there is an inflection point at x = 270
15. (a) x =−2, 2
(b) increase: −2 < x < 2, decrease: x < −2, x > 2
(c) min at x =−2, max at x = 2
(d) up: −
√
12 < x < 0, x >
√
12;
down: x < −
√
12, 0 < x <
√
12
(e) x =−
√
12, x = 0, x =
√
12
17. min =−5atx = 1, max = 76 at x = 4
19. min = 0atx = 0, max = 3
4/5
at x = 3
21. local max at x =−
4
3
−
√
10
3
, local min at x =−
4
3
+
√
10
3
23. local max at x ≈ 0.2553, local min at x ≈ 0.8227
27. min at x =−3, inflection points at x =−2, x = 0
⫺
5
⫺
30
5
30
y
29. min at x =−1
⫺
55
⫺
40
60
y
31. min at x =−1, max at x = 1,
inflection points at x =−
√
3, x = 0, and x =
√
3,
horizontal asymptote at y = 0
⫺
5
⫺
2
5
2
y
33. min at x = 0, inflection points at x =−
1
3
, x =
1
3
horizontal
asymptote at y = 1
⫺
3
⫺
1
3
3
y