A company's costs and revenue in dollars for one product are modeled by the following functions, where x is the number of items produced.

C(x) = 3x and R(x) = 8x -(x^2/1000)

c(x) is the cost function
r(x) is the revenue function

From these two we can find, marginal cost, marginal revenue, marginal profit, values that make marginal profit 0 and the amount of revenue, cost, and profit when marginal profit is 0.