Not sure if this belongs in this forum but help would be appreciated... if someone could walk me through the process of finding out both a and b not just give me the answer... Thank you

A storage box with a square base must have a volume of 8 cubic feet. The top and bottom cost 2 dollars per square foot and the sides cost 1 dollar per square foot.

a) Find a a function C(x) that represents the cost of the box, where x represents the length of a side of the base.

b) Find the critical numbers x of the cost function found in part 2a and use the first derivative test to classify them as a relative maximum, relative minimum or neither. Be sure to label your functions appropriately and circle your final answers rounded out to three decimal places.