Find the maximum of the function f(x,y)= -(x-a)^2 - (y-b)^2 subject to the constraint y=kx.

So here's where I'm at:

1. δf/δx = -2(x*-a) ; δf/δy = -2(y*-b) (* means for a particular x or y)

2. g(x,y) = y-kx = 0

3. δg/δx = -λ ; δg/δy = λ

And then from here, I'm not really sure where to go. Any suggestions? Thanks,

Kim