Hello,

I'm trying to find the set of all points z such that the function f is differentiable. I am having trouble comprehending the steps one needs to take. I have been playing around with the Cauchy-Riemann equations but to little success. The two different functions I am having trouble with are:

1) f(x + iy) = 2x + ixy^2

2) f(z) = cos(z*), where z* is z conjugate

Thank you for your time.