1. The problem statement, all variables and given/known data An open-top box is to be made so that its width is 4 ft and its volume is 40 ft^3. The base of the box costs $4/ft^2 and the sides cost $2/ft^2. a. Express the cost of the box as a function of its length l and height h. b. Find a relationship between l and h. c. Express the cost as a function of h only. d. Give the domain of the cost function. e. Use a graphing calculator or computer to approximate the dimensions of the box having least cost. 2. Relevant equations NONE 3. The attempt at a solution a. I got that. f(l,h) = 8lh + 16l. b. I got that. lh = 10 or l = 10/h. c. What the living hell???????? d. I have 1000% ABSOLUTELY no idea whatsoever. e. This bugs me. The lower the length is, the lower the total cost. I answered 0.000...01 (infinite). This way the cost is lowest. But it seems so illogical! This is my Precalculus summer assignement. I can't get these hard-as-hell problems wrong. I need this urgently and ASAP!!! Thanks in advance.