According to the principle of MR=SMC, monopoly manufacturers adjust the output and price to P0 and Q0 respectively. Monopolists can make a profit in the balanced output Q0. 0, at this time, the maximum profit of AR & gtSAC is equivalent to the shadow area in the figure; Monopoly manufacturers can also lose money, that is, л < 0, as shown in Figure (b). At this time, AR < SAC, and its maximum deficit is equivalent to the shaded part in the figure. In the case of loss, the monopoly manufacturer needs to decide whether to continue production according to the comparison between AR and AVC: when AR >: AVC, the monopoly manufacturer will continue production; When ar < AVC, the monopoly manufacturer must stop production; When AR=AVC, the monopolist is at the critical point of production and non-production. Because AR < AVC, the monopolist stopped production.
Therefore, the short-term equilibrium condition of monopoly manufacturers is: MR=SMC, and its profit can be greater than zero, less than zero or equal to zero.
Microeconomics, fifth edition, 178 with pictures.