Question

the radius of a right cylinder is increasing at the rate of 9in./sec, while the height is decreasing at the rate of 7in./sec. at what rate is the volume of the cylinder changing when the radius is 15in. and the height is 18in.?

Answer 1

Volume = pi * radius^2 * height
V = pi r^2 h
Rate of change of volume means change of volume with respect to time.
So you need to calculate dV/dt. Can you write dV/dt ?