Question Number 30589 by abdo imad last updated on 23/Feb/18
$${let}\:{U}_{{n}} =\:\left\{{z}\in{C}\:/\:{z}^{{n}} =\mathrm{1}\right\}\:\:{find} \\ $$$${S}=\:\sum_{{z}\in{U}_{{n}} } \:\:\frac{{z}}{\left({x}−{z}\right)^{\mathrm{2}} }\:\:. \\ $$
let-U-n-z-C-z-n-1-find-S-z-U-n-z-x-z-2-