A company has found that the marginal cost (in thousands of dollars) to produce x central air conditioning units is 60x C'(x): 5x2 +e where x is the number of uhits produced. a) Find the cost function, given that the company incurs a fixed cost of $10,000 even if no units are built. b) The company will seek a new source of investment income if the cost is more than $20,000 to produce 5 units. Should they seek this new source? Explain.