Suppose that the cost function for a commodity is C(x) = 80 + x2 dollars. (a) Find the marginal cost at x = 9 units. m9) = E Tell what this predicts about the cost of producing 1 additional unit. The cost to produce the 10th unit is predicted to be $ |:| . (b) Calculate C(10) - C(9) to find the actual cost of producing 1 additional unit. $|:|