Question Number 28363 by abdo imad last updated on 24/Jan/18
$${simlify}\:{the}\:{sum}\:\:\:{S}=\:\sum_{{k}=\mathrm{0}} ^{{n}−\mathrm{1}} \:\:\frac{{x}+\:{e}^{{i}\mathrm{2}{k}\pi} }{{x}\:−{e}^{{i}\mathrm{2}{k}\pi} }\:\:. \\ $$
Answered by ajfour last updated on 24/Jan/18
$${S}=\frac{{n}\left({x}+\mathrm{1}\right)}{{x}−\mathrm{1}}\:. \\ $$