53. Suppose that a rectangular box has volume 324 cm and a square base of edge length x centimeters. The mate- rial for the base of the box costs 2/cm, and the material for its top and four sides costs 1/cm. Express the total cost of the box as a function of x. See Fig. 1.1.20. X r A Fig. 1.1.20 V = xy (Problem 53)