Question Number 77147 by Rio Michael last updated on 03/Jan/20
$$\:\underset{{r}=\mathrm{1}} {\overset{\infty} {\sum}}\frac{\mathrm{1}}{{r}^{{k}} }\:{is}\:{divergent}\:{for}: \\ $$$${A}.\:{k}\:\leqslant\:\mathrm{1} \\ $$$${B}.\:{k}\:>\:\mathrm{2} \\ $$$${C}.\:{k}\:\leqslant\:\mathrm{2} \\ $$$${D}.\:\mathrm{0}\:\leqslant\:{k}\:<\:\mathrm{2} \\ $$
Commented by JDamian last updated on 03/Jan/20
$${A} \\ $$