Question

the side of a cube is expanding at a constant rate of 2 centimeters per sesond. what is the instantaneous rate of change of the surface area of the cube, in cm2 per second, when its volume is 27 cubic cm

Answer 1

For a cube, SA = 6s^2. Differentiate with respect to time.

dSA/dt = 12s(ds/dt)

ds/dt is given as 2cm/s.
When V = 27cm^3, s = 3cm. dSA/dt=?

Answer 2

72