1. 22–23. Choices of variables may vary. 22. P( ) = 8 23. E(h) = 7.10h
Direct Variation
ALGEBRA 1 LESSON 5-5
pages 264–267  Exercises
1. no
2. no
3. yes; –2
4. no
5. yes;
6. yes;
7. yes; –
8. yes; 0.5
9. yes; –
10. y = 5x
11. y = x
22–23. Choices of variables may vary.
22. P( ) = 8
23. E(h) = 7.10h
24. yes; y = 1.8x
25. no
26. yes; y = –1.5x
27. a. or
b. = , 52 lb
28. = , 9 mi
29. y = x
30. y = –20x
12. y = – x
13. y = x
14. y = – x
15. y = – x
16. y = – x
17. y = – x
18. y = – x
19. y = 2x
20. y = – x
21. y = x 5 4 9 5 3 2 1 6 5 6 4 3 7 3 50 20 5 2 4 3 1 10 50 20
130 x 4 3 10 3 30 x 3 2 1 6 2 3 1 5 1 5
5-5

2. b. A line through the origin that is neither vertical nor
Direct Variation
ALGEBRA 1 LESSON 5-5
31. y = – x
32. y = 6x
33. y = 9x
34. y = – x
35. y = – x
36. y = x
37. a. The ratio is the
same for each pair
of values.
b. A line through the origin
that is neither vertical nor
horizontal is the graph of
a direct variation. 36 25
38. True; a line that is neither horizontal
nor vertical can pass through
(0, 0) and (–2, 4).
39. False; the line through (0, 3) and (0, 0)
is vertical, so it is not a function and is
therefore not a direct variation.
40. True; for the equation y = kx, if one side
is multiplied by 3, then the other side must
be multiplied by 3.
41.
y = x 1 32 15 52 27 64 y x 5 2
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3. Direct Variation 44. y = x 45. a. b. b = w c. Check students’ work.
ALGEBRA 1 LESSON 5-5
44.
y = x
45. a.
b. b = w
c. Check students’ work.
46. a. 48 volts
b ohms
47. 12
48. –8
49. 8
50. –6
51. 5
52. 2
53. a. c = 1.83g; yes
b. c = m or
c = m
54. A
55. H
56. A
57. B
58. C
42.
y = – x
43. 5 2 5 2
1.83 24 1 32 1 32 5 2
5-5

4. [1] correct answer but no work shown 60. y = 3x 61. y = x
Direct Variation
ALGEBRA 1 LESSON 5-5
59. [2] y = kx
–4 = k(–1)
4 = k
y = 4x
[1] correct answer but no work shown
60. y = 3x
61. y = x
62. y = 12 – x
63. y = x
64. r > –18
65. c –1.8
66. m < –3
67. a
68. n < –80
69. t
70. v –
71. b >
72. 15,600 ships 5 2
> –
> – 1 2 1 3 1 6
< –
> –
5-5