How fast is the surface area changing when each edge is 6 centimeters and 12 centimeters?

Question

All edges of a cube are expanding at a rate of 4 centimeters per second.

*Please have two answers ( One for 6cm and another for 12cm)

Answer 1

Let x = length of an edge of the cube

dx/dt = 4

S = 6x² = surface area

dS/dt = 12x(dx/dt)

So, when x = 6 cm, dS/dt = 12(6)(4) = 288 cm²/sec.

Plug in 12 for x to get the other answer.