Question Number 54369 by maxmathsup by imad last updated on 02/Feb/19
$${find}\:{lim}_{{x}\rightarrow\mathrm{1}} \:\left(\xi\left({x}\right)−\frac{\mathrm{1}}{{x}−\mathrm{1}}\right) \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 03/Feb/19
$${what}\:{is}\:\xi\left({x}\right)… \\ $$
Commented by maxmathsup by imad last updated on 03/Feb/19
$$\xi\left({x}\right)=\sum_{{n}=\mathrm{1}} ^{\infty} \:\frac{\mathrm{1}}{{n}^{{x}} }\:\:{with}\:{x}>\mathrm{1}\:. \\ $$