i) If `(a-ib)^{1/3} = p-iq` (where `a,b,p,q \in \mathbb{R}`) then show that `(a+ib)^{1/3}=p+iq`
ii) If `(x-iy)^{1/3} = a-ib` (where `x,y,a,b \in \mathbb{R}`) then show that `x/a + y/b = 4(a^2-b^2)`