Help with this calc 1 question

160 All boxes with a square base, an open top, and a volume of 40 fto have a surface area given by S(x) = x + y , where x is the length of the sides of the base. Find the absolute minimum of the surface area function on the interval (0,co). What are the dimensions of the box with minimum surface area? Determine the derivative of the given function S(x). 160 S'(X) = 2X - x2 The absolute minimum value of the surface area function is ft2. (Round to three decimal places as needed.) The dimensions of the box with minimum surface area are a base of length ft and a height of ft. (Round to three decimal places as needed.)