1) The document discusses applications of calculus concepts like marginal revenue, average revenue, and marginal cost in economics. 2) It provides examples of calculating marginal revenue from demand functions, finding the quantity where marginal revenue is zero, and deriving a demand function from a marginal revenue function. 3) One example shows calculating the total increase in cost from increasing production from 100 to 200 units using a given marginal cost function and total cost function.