I have developed the formula to determine the radius of a cylinder with a fixed volume:
$ f(x) = \sqrt[3]{\dfrac{V}{\pi}}\ $
Substituted into the formula for the surface area of a cylinder, I get the following function. This would give me the minimum surface area of a cylinder for a given volume.
$ S(V) = 2\pi(\sqrt[3]{\dfrac{V}{\pi}})^2+2\pi(2 * \sqrt[3]{\dfrac{V}{\pi}}) $
However, my assignment for class asks for a rational function for this problem. How could I take my existing function and make it rational?