Mathe

Question 4 > 0/10 pts 5 3 2 4 0 Textbook @ Videos [+] A box with a square base and open top must have a volume of 48668 cm . We wish to find the dimensions of the box that minimize the amount of material used. First, find a formula for the surface area of the box in terms of only a, the length of one side of the square base. [Hint: use the volume formula to express the height of the box in terms of a. ] Simplify your formula as much as possible. A(x) Next, find the derivative, A'(x). A'(x) = Now, calculate when the derivative equals zero, that is, when A'() = 0. [Hint: multiply both sides by a? . ] A'(x) = 0 when a = We next have to make sure that this value of a gives a minimum value for the surface area. Let's use the second derivative test. Find A"(x). A"(z) = Evaluate A"(x) at the x-value you gave above. NOTE: Since your last answer is positive, this means that the graph of A() is concave up around that value, so the zero of A' (a) must indicate a local minimum for A(). (Your boss is happy now.) Submit