Question

side of the cube increasing at rate of 6 cm/s. find the rate of increase of the volume when the length of a side is 9 cm.[ans 1458cm^3/s]

my answer:
~729x6=4374cm^3/s
i need some1 show me the calculation if im wrong.

Answer 1

V = x^3
dV/dx = 3 x^2
so
dV/dt = 3 x^2 dx/dt

dV/dt = 3 * 81 * 6 = 1458 cm^3/s

Answer 2

A side of a cube is constantly increasing at a rate of 6 cm/sec. Find the rate of increase in volume and surface area when the one side of the cube is 12 cm.