1. Using Cauchy-Riemann equations of Cartesian form find the derivative (i.e f'(z)) of f(z) = z^2.
2. Show that the function f(z) = re^{i heta} has a derivative everywhere in its domain using the Cauchy-Riemann equations of polar form.
3. Show that u(x, y) = xe^x cos y - ye^x sin y is harmonic.
4. Find the harmonic conjugate v(x, y) of u(x, y) where u(x, y) = xe^x cos y - ye^x sin y.
5. Using Cauchy-Riemann equations determine whether f(z) = z^3 is analytic or not.