Direct, Inverse, and Joint Variation

Select all the equations that represent a direct variation:

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Does the following table represent direct variation?

• Yes

• No

Does the following table represent direct variation?

• Yes

• No

The value of y is directly proportional to the value of x.

If y = 132 when x = 11, what is the value of y when x = 17?

• y = 144

• y = 12

• y = 204

• y = 71

The value of y varies directly with x. If x = 195 when y = 15, what is the value of x when y = 9?

• y = 1.44

• y = 117

• y = 12

• y = 135

Write an equation for this relationship.

• y = 4x
• y = 1/8x
• y = 1/4x
• y = 8x

In a direct variation, y = 39 when x = 3. 
Find the value of y when x = 2.

• 26
• 3
• 58.5
• 2

If y varies directly with x, and y = -20 when x = 3, what is y when x = 15?

• 100

• -2.25

• 2.25

• -100

If y varies directly with x, and y = 8 when x = 3, what is x when y = -56?

• 21

• -21

• -149.33

• 149.33

If y varies directly with x, and y = 21 when x = -7, what is y when x = 42?

• -126

• 14

• -14

• 126