Question

y varies directly as the square of x and inversely as z. If y = 12 when x = 2 and z = 7, find y when x = 4 and z = 4.

Answer 1

84

Explanation:

The initial statement is y directly proportional to x square and inversely proportional to z

to convert an equation multiply by k the constant of variation

y=k*((x*x)/z)

K x square/z

to find k use the given condition

y=12 when x=2and z=7

y= k x square /z

yz/x square = k

12*7/4

84/4

21

equation is y = 21x square / z

when x=4 and z= 4

y= 21*16/4

84 is the answer