I have developed the formula to determine the radius of a cylinder with a fixed volume:

$f(x)=\sqrt[3]{{\displaystyle \frac{V}{\pi}}}\text{}$

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.

$S(V)=2\pi (\sqrt[3]{{\displaystyle \frac{V}{\pi}}}{)}^{2}+2\pi (2\ast \sqrt[3]{{\displaystyle \frac{V}{\pi}}})$

However, my assignment for class asks for a rational function for this problem. How could I take my existing function and make it rational?

$f(x)=\sqrt[3]{{\displaystyle \frac{V}{\pi}}}\text{}$

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.

$S(V)=2\pi (\sqrt[3]{{\displaystyle \frac{V}{\pi}}}{)}^{2}+2\pi (2\ast \sqrt[3]{{\displaystyle \frac{V}{\pi}}})$

However, my assignment for class asks for a rational function for this problem. How could I take my existing function and make it rational?