z varies directly as x^2. If z=36 when x=3,find zwhen x=4.

Answer 1

z varies directly as x^2 -----> z = kx^2 , where k is a constant

if z=36, x = 3
336 = k(9)
k = 4

so y = 4x^2
when x=4 , y = 4(16) = 64

or , by ratio ....

z1/z2 = x1^2/x2^2

z1/36 = 4^2/3^2
z1 = 36(16/9) = 64