I need to find the rate of change of the volume of a sphere with respect to the radiusr.

Is the answer 4πr²

I know the volume of a sphere is (4πr³) / 3

And that dV/dr= (4π/3)(3r²) = 4πr²

Ifrwas defined I would plug in the value for it and go through the rest of the problem, but since its not defined is that the final answer?