so for example:
W(x,y,z)=(x+y,2xy^2)
J=2y(2x-y)
has no inverse where y=0 and y=2x, but has an inverse everywhere else?
So if i wanted to show that these vector fields are differentiable what do I have to do?
lim(h->0) (f(x+h)-f(h))/h
and then the same for y? but since it's a vector i cannot devide by this...