For the following functions, show that they are harmonic on C and find a harmonic conjugate. You may do this by checking Laplace's equation and integrating the Cauchy-Riemann equations, or by finding an analytic function which has u as its real part. (a) u(x, y) = x3 - 3xy2 +y (b) u(x,y) = sin x cosh y (c) u(x,y) = Imezz