Direct & Inverse

The width of a rectangle varies inversely with its length.  If the width is 6 when the length is 24, give an equation that shows the relationship.

• y = 4x

• y = 144x

• y = 4/x

• y = 144/x

Y is directly proportional to the square of z and inversely proportional to w.

• y=kz²/w

• y=kz/w

• y=w/kz²

• y=w/kz

y varies directly with the square of x.  If y=40 when x=4, find y when x = 7

• 17.5

• 70

• 122.5

a varies inversely as the square of b. If a is 1 when b is 3, find a when b is 5. 

• 0.36

• 9

• 25

• 36

y varies directly as the square of x and indirectly with z. If y is 8 when x is 4 and z is 6, find y when x is 8 and z is 4.

• 3

• 12

• 48

• 64

y varies directly as x, if y=12 when x=5, find y when x=3

• 36/5

• 15/12

• 12/5

• 12/15

y varies inversely as x, if y = -3 when x = -6, find y when x = 14.

• 11

• -11

• 9/7

• 7/9

Which equation represents an inverse variation?

• y = 40/x

• y = 40x

• y/x = 40

• x = y/40

Which equation below represents a direct variation?

• y = -2x

• y = -3x -5

• y = -1

• x + 3y = 15

The image is an example of the graph of a(n)

• direct variation

• inverse variation

• neither

• both