11. Suppose that C(x) is the total cost of producing x units of a particular commodity and p(x) is the unit price at which all x units will be sold. Assume p/fx) and C(x) are in dollars. a. Find the marginal cost and the marginal revenue. b. Use marginal analysis to approximate the cost of the 21st unit. c. Find C(21)-C(20). What does this represent? Compare your answer with that to part Use marginal analysis to estimate the revenue derived from the sale of the 21st unit. What is actual revenue obtained from the sale of the 21st unit? d. 12 2x c(x) = 4x2 + 43;p(x)--34x