Equilibrium/Profit-Maximization : Monopoly

Profit equals total revenue minus total costs.
Profit = TR – TC - (1)
Multiplying and dividing (1) by Q
Profit = (TR/Q - TC/Q) x Q
Profit = (P - AC) x Q

The monopolist will receive economic profits as long as price is greater than average total cost

A monopolist firm firm will choose to produce an output where
• MC = MR
• MC curve cuts MR from below.



Here, E is the point of equilibrium. At E ,
1. MC=MR
2. MC cuts MR from below.

• From E, Draw a line perpendicular to X axis till AR curve. This will tell us the price, (price is OA over here.)
• the point of intersection of this perpendicular line and AC curve , ie point D, tells us the average cost.So, the cost is OB over here.
• we know that Profit = (P - AC) x Q
• Profit is rectangle ABCD.

A monopolist firm will earn super normal profits in the short run as well as the long run.