Question Number 45517 by maxmathsup by imad last updated on 13/Oct/18
$${find}\:{S}\left({x}\right)=\sum_{{n}=\mathrm{1}} ^{\infty} \:\:\frac{{x}^{{n}} }{{n}^{\mathrm{2}} }\:\:{with}\:\mid{x}\mid<\mathrm{1}\:\:. \\ $$
find-S-x-n-1-x-n-n-2-with-x-lt-1-