tal If the cost function for a commodity is C(x) = 1x3 + 2x + 2x + 20 dollars 90 find the marginal cost MC at x = 3 units. (Round your answer to two decimal places.) MC = $ Tell what the marginal cost predicts about the cost of producing 1 additional unit. The cost of producing 1 additional unit is $ Tell what the marginal cost predicts about the cost of producing 2 additional units. The cost of producing 2 additional units is $