Algebra II
posted by Reanna .
Suppose that y varies directly as the 3/2 power of x, and that y=192 when x= 16. find y when x=9.

y = k * x^(3/2)
192 = k * 16^(3/2)
192 = k * 4^3
192 = k * 64
k = 3
so
y = 3 x^(3/2)
if x = 9
y = 3 * 3^3
y = 3^4
y = 9*9
y = 81