O Area A = 1,269 Calculate the definite integral f(x) dx by referring to the figure on the right with the indicated Area B = 2,387 Area C = 3,106 areas. a B C/D X Ab Area D = 1,897 [f(x) dx = (Simplify your answer.)K A company manufactures mountain bikes. The research department produced the marginal cost function C'(x) = 400 - 7, 0S x$ 900, where C'(x) is in dollars and x is the number of bikes produced per month. Compute the increase in cost going from a production level of 300 bikes per month to 600 bikes per month. Set up a definite integral and evaluate it. The increase in cost is $