I am facing another problem that I can't compute the extremes forDoh)

f(xy)=e^{x}(x^{2}-y^{2})

so far I have:

fx= 2xe^{x }+ e^{x}(x^{2}-y^{2})

fy= -2ye^{x }fxx=2e^{x}+2xe^{x}+ e^{x}(x^{2}-y^{2}) + 2xe^{x }

fyy= -2e^{x }fxy= -2ye^{x How do I find the extremes? I set fx and fy to 0, but I can't solve for x and y. Thanks for any help.}