申論題

5.The weekly cost to produce x widgets is given by C(x) = 75000 + 100x - 0.03x² + 0.000004x³, 0 ≤ x ≤ 10000 and the demand function for the widgets is given by p(x) = 200 - 0.005x, 0 ≤ x ≤ 10000. Assume that the company sells exactly what they produce.

(b)What are the marginal cost, marginal revenue and marginal profit when 7500 widgets are sold?