Suppose two firms compete by choosing advertising levels A1and A2. The profit functions of each firm are given by:

1(A1, A2) = 10A1+ a A1A2- A1^2

and

2(A1, A2) = 10A2+ a A1A2- A2^2,

whereais a constant strictly between 0 and 1.

Firms choose advertising levels simultaneously and once-and-for-all.

(a)Solve for the best response functions of each firm and plot them on a graph. Find the Nash equilibrium levels of advertising, and the associated profit levels. Identify the Nash equilibrium on your graph.

(b)Imagine that firm 1's profit function is changed to1(A1, A2) = 11A1+ a A1A2- A1^2,while 2's profit function is unchanged. Without redoing the math, explain using graphs of the old and new best response functions how the equilibrium would change.

I solved (a) A1=A2=10/2-a and got the graph, but I do not know how to do (b)