In: Economics
An industry contains two firms, one whose cost function is C(y) = 30y and another whose cost function is C(y) = y2. The inverse demand function for the firms' output is p = 120 -Q, where Q is the total output. What are the firms' outputs in a Nash equilibrium of Cournot's model? Graph the best response functions for Firm 1 and Firm 2.
The inverse demand is given to be
, and for
, we have
, where q1 and q2 are quantities of the respective firms.
Firm 1 have the cost function
, and its marginal cost would be
. The total revenue of firm 1 would be
, and the marginal revenue would be
. The profit maximization would occur where the MC is equal to MR,
ie
or
or
. This is the BR function of firm 1.
Firm 2 have the cost function
, and its marginal cost would be
. The total revenue of firm 2 would be
. and the marginal revenue would be
. The profit maximization would occur where the MC is equal to MR,
ie
or
or
.
The cournout (nash) equilibrium would occur where the BR
function intersects. Putting the first BR function into the second
one, we have
or
or
or
, and since
, we have
. These are the required equilibrium output.
The graph is as below.