If C(x) is the total cost function of producing x items, then the marginal cost at x = a, given by C'(a), is the approximate cost to produce the (a + 1)st item. If the cost of producing x golf carts is C(x) = 0.001x^(3) + 0.2x^(2) + 39x + 300 what is the cost of producing 40 golf carts?