Suppose that the average cost, in dollars, of producing a shipment of a certain product is Č = 5,000x + 20,000, x>0 where x is the number of machines used in the production process. (a) Find the critical values of this function. (Assume 0 < x < co. Enter your answers as a comma-separated list.) (b) Over what interval does the average cost decrease? (Enter your answer using interval notation.) (c) Over what interval does the average cost increase? (Enter your answer using interval notation.) Need Help? Read It Talk to a Tutor