Hey echodot.
What is the function g in this case?
The question goes like this:
Use the chain rule to verify the identity y * (∂g/∂x) + x * (∂g/∂y) = 0 if g(x,y) = f(x^2 - y^2, y^2 - x^2) and f is differentiable.
No answer key to help, so any support would be appreciated, thanks!