Direct and Inverse Variation

WORKSHEET 8.1 ¨C Direct and Inverse Variation

Name: _____________________________________ Hour: __________ Date: __________________

SECTION 1: Tell whether x and y show direct variation, inverse variation, or neither.

1) y = -9x

2) y =

direct

4) x + y = -7

neither

3) y =

inverse

5) 15y = x

x+8

neither

6) xy = 6

inverse

direct

SECTION 2: Given that x and y vary directly, use the specified values to write a direct

variation equation that relates x and y. Then find the value of y for the given value of x.

8) x = 4, y = -20

Find y when x = -6

9) x = -54, y = -9

Find y when x = 3

y = -5x

y=

y = 30

y=

1

6

1

2

x

10) x = -15, y = 6

Find y when x = 100

y=-

2

5

x

y = -40

SECTION 3: Given that x and y vary inversely, use the specified values to write an inverse

variation equation that relates x and y. Then find the value of y for the given value of x.

11) x = 4, y = -2

Find y when x = -2

12) x = -

,y=

Find y when x = 5

-8

x

y=-

y=4

y=-

y=

1

4x

1

20

13) x =

, y = 20

Find y when x = -32

y=

4

x

y=-

1

8

SECTION 4: Decide if the data shows direct variation, inverse variation, or neither. If it shows

variation, write an equation to relate the variables.

14)

15)

direct

y=

17)

3

2

16)

neither

inverse y =

x

direct

y = -3x

18)

neither

19)

inverse

y=

20)

72

x

inverse

y=

12

- x

100

x

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