$8$ Show that the function $u$ given $as$ under $is$ Harmonic. Find the

conjugate function $v$ and express $u+ivasan$ analytic function $of$

$z.(i)u=e^{-2xy}sin(x^2-y^2)(ii)u=x^3-3x{y}^2$

$(iii)u=(x-1{)}^3-3x{y}^2+3y^2$