Question

A closed rectangular box has volume 32 cm3 . what are the lengths of the edges giving the minimum surface area?

Answer 1

   
The minimum area is obtained if the box is a cube.
⇒  The lengths of the edges are:

$\displaystyle\\ l= \sqrt[\b3]{32} = \sqrt[\b3]{8 \times 4} = \boxed{2\sqrt[\b3]{4}~~cm}$