. (10 points) An open cardboard box has rectangular sides with no top. It has a volume of 4 cubic meters. {a} (3 points) Express the total surface area of the 5 sides in terms of the length l? and the width 13 of the bottom side. (b) {4 points) 'What should the length E? and the width a: be so that the smallest amount of cardbon is used? i.e., Find if? and is where S has the local minimum. Explain wh}r S has the local minimum at such E and w. (c) {3 points) Let f = 1 and w = 1. Estimate how much 3 changes when we increase if to 3+ 0.1 and decrease in to w [1.2