Question

3.) If y vanes inversely as x, and y = 9 when x = 4, find y when x =12

Answer 1

y= 36

Explanation:

if y varies directly as x, and y=9 when x=4, find y when x=16

.

When you see "direct variation" think:

y = kx

.

To find k, use "y=9 when x=4":

y = kx

9 = k(4)

9/4 = k

.

so, our equation is:

y = (9/4)x

.

now, we can answer:

find y when x=16

y = (9/4)x

y = (9/4)(16)

y = (9)(4)

y = 36