Log in to add a comment

Log in to add a comment

-14 is the correct answer.Because -18/9 = -2 so 7 x -2 = -14

Assuming it's a

y varies directly with x. If y = -18 when x = 9, find y when x = 7.

y = kx

-18 = k (9)

-18/9 = k (9)/9

-2 = k, constant of direct variation.

To solve for y, use the constant of variation, -2 when x = 7

y = -2(7)

y = -14, final answer.

Assuming it's an inverse variation:

y varies inversely with x. If y = -18 when x = 9, find y when x=7.

y = k/x

-18 = k/9

k = (9) (-18)

k = -162, the constant of inverse variation

Using the constant -162 for y = ? when x = 7

y = k/x

y = -162/7

y = -162/7 or -23 1/7

See the difference in y values?