Find f such that f'(x) = f(9) = 63. VX f(x) =A company determined that the marginal cost, C'(x) of producing the xth unit of a product is given by C'(x) = x" - 6x. Find the total cost function C, assuming that C(x) is in dollars and that fixed costs are $5000. - . . C(x) =A company finds that the rate at which the quantity of a product that consumers demand changes with respect to price is given by the marginai-demand function 3000 X2 where x is the price per unit: in dollars. Find the demand function if it is known that 1002 units of the product are demanded by consumers when the price is $3 per unit. D'(x)= [300 = dE The rate at which a machine operator's efficiency, E (expressed as a percentage), changes with respect to time t is given by - =30 -10t, where t is the number of hours the operator has been at work. a) Find E(t), given that the operator's efficiency after working 2 hr is 73%; that is, E(2) = 73. b) Use the answer in part (a) to find the operator's efficiency after 3 hr; after 5 hr. a) E(t) =