College Algebra
posted by Ally .
y varies directly as the third power x and inversely as Z. If y=16 when x=4 and z=8,find y when x=9 and z=6

y = (kx^3)/z
substituting the given values to find the constant k,
16 = k(4^3)/8
16 = k(64)/8
16 = 8k
k = 2
therefore,
y = (2x^3)/z
if x = 9 and z = 6,
y = 2*(9^3)/6
y = 243
hope this helps~ :)