3-4 Direct Variation
Name the constant of variation for each equation. Then find the slope of the line that passes through each
pair of points.
11. ANSWER: –5;–5
13. ANSWER: 15. ANSWER: –12;–12
Graph each equation.
17. y = –7x
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15. ANSWER: 3-4 Direct
Variation
–12;–12
Graph each equation.
17. y = –7x
ANSWER: 19. ANSWER: 21. ANSWER: 23. ANSWER: eSolutions Manual - Powered by Cognero
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3-4 Direct Variation
23. ANSWER: Suppose y varies directly as x. Write a direct variation equation that relates x and y. Then solve.
25. If y = 22 when x = 8, find y when x = –16.
ANSWER: 27. If y = 12 when
, find x when y = 16.
ANSWER: CCSS SENSE-MAKING Certain endangered species experience cycles in their populations as shown in
this graph. Match each animal to one of the colored lines in the graph.
34. red grouse, 8 years per cycle
ANSWER: red
35. voles, 3 years per cycle
ANSWER: dark green
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36. lemmings, 4 years per cycle
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34. red grouse, 8 years per cycle
ANSWER: 3-4 Direct
red Variation
35. voles, 3 years per cycle
ANSWER: dark green
36. lemmings, 4 years per cycle
ANSWER: blue
37. lynx, 10 years per cycle.
ANSWER: lime green
Write and graph a direct variation equation that relates the variables.
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38. PHYSICAL SCIENCE The weight W of an object is 9.8 m/s times the mass of the object m.
ANSWER: W = 9.8 m
39. MUSIC Music downloads are $0.99 per song. The total cost of d songs is T.
ANSWER: T = 0.99d
40. GEOMETRY The circumference of a circle C is approximately 3.14 times the diameter d.
ANSWER: C = 3.14d
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3-4 Direct Variation
40. GEOMETRY The circumference of a circle C is approximately 3.14 times the diameter d.
ANSWER: C = 3.14d
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