ECON 301 Notes 10
Intermediate Microeconomics MONOPOLY BEN VAN KAMMEN, PHD PURDUE UNIVERSITY Price making A monopoly seller in a goods market is the conceptual opposite from perfectly competitive firms. ◦ The monopolist does not face competition from other firms because he is the only seller. ◦ He is still constrained in his behavior, however, by consumers’ willingness to pay for his output, i.e., by the demand curve. A monopolist faces the entire market demand for his good, though, so when he chooses an output level, he implicitly determines the price. ◦ Thus the term “price maker”. Competitive firm’s demand curve Monopolist’s demand curve Total revenue Competitive firms get the same price for all units sold, so: = . ∗ If a monopolist wants to sell more, he has to cut the price on all units sold. TR is still equal to , but P* is now a function of Q. ◦ Note: Q as market quantity∗ as distinct from q for firm’s quantity. Specifically the demand curve tells you P* as a function of Q. Example Say that market demand is given by: 1 = 10 20 2 . and the inverse demand you see− on Marshall’s diagram: = 200– 20 . 1 2 = , where P is given by the inverse demand function. = 200 20 . 1 = – 20 2. − 3 2 Taking the partial derivative 200 to get MR: = 200 30 . 1 2 − MR is below the price q* The product rule in calculus The basic reason that < for a firm facing downward- sloping demand has to do with the product rule in calculus. The product rule is as follows: when you multiply two functions of the same variable together, the differential of the product is: ( ) ( ) ( ) = ℎ ≡ +∗ ℎ � � The product rule in calculus So if ( ) = , and ( ) = [ ] = ( ), = , and = = ∗ + .
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