1. Writing a Function Rule
ALGEBRA 1 LESSON 5-4
pages 256–259  Exercises
1. B
2. A
3. C
4. ƒ(x) = 3x
5. ƒ(x) = x – 0.5
6. ƒ(x) = 0.5x
7. ƒ(x) = –3x
8. y = 4x
9. y = x 2
10. t(c) = 0.79c
11. d(n) = 45n
12. ƒ(h) = h
13. e(n) = 6.37n
14. A(n) = n2
15. V(n) = n3
16. A(r) = r 2
17. a.ƒ(x) = 0.19x
b. $1.52
18. a. ƒ(x) = (x – 1)
b. $.97
19. ƒ(x) = 1000x
20. ƒ(x) = 2.54x 1 12
21. a. C(a) = 10a + 1
b. $31
c. 61; the total cost of
12 books
22. a. C(b) = 6b
b. 72; the total cost of
c. about $5.08
d. Club; $61 is less
than $72.
23. Answers may vary.
Sample: The input
values you need
may not be in the table.
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2. Writing a Function Rule
ALGEBRA 1 LESSON 5-4
24. a. gal of water, number
of loads
b. w(n) = 34n
c. 238 gal
d. 13 loads
25–28. Tables may vary.
Samples are given.
25.
ƒ(x) = x
26.
y = x + 3
27.
y = –x + 2
28.
y = x
29. Answers may vary. Sample:
ƒ(x) = 60x; ƒ(3) = 180,
180 mi in 3 h, the distance
you can travel at a constant
speed of 60 mi/h
30. a. 0.15b
b. c(b) = 1.15b
c. $20.70
31. ƒ(x) = x3
32. ƒ(x) = –x3
33. ƒ(x) = –x3 – 1
34. a. c(m) = m
b. $70.60, $89.60
c. 38 mi
d. $202 3 2 1 2 2 3
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3. Writing a Function Rule
ALGEBRA 1 LESSON 5-4
35. a. B(v) = 6.93v
b. B(w) = w
36. A
37. H
38. D
39. B
40. C
41. [2] D = 0.1w 2 + 5w
D = 0.1(60)2 + 5(60)
D = 0.1(3600) + 300
D = 660  
The dosage is 660 mg.
[1] correctly substitutes
60 for w but makes a
minor calculation error
42–47. Tables may vary. Samples are given.
42.
43. 7 10
5-4

4. Writing a Function Rule
ALGEBRA 1 LESSON 5-4
44.
45.
46.
47.
48. 17%; increase
49. 2%; increase
50. 8%; decrease
51. 83%; decrease
52. 29%; increase
53. 42%; decrease
54. a. 2 oranges;
3 oranges
b. 28 tbsp
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