Problem 7. Let f(&) be a function of a complex variable x = a + iy.
申論題內容
(b) Assume that u(x, y) = x3 +3xy2. Show that it is impossible to find a real-valued function v(x, y) such that f(z) = u(x,y) + iu(x,y) is differentiable with respect to z for all z .