Question Number 161553 by qaz last updated on 19/Dec/21
$$\underset{\mathrm{t}\rightarrow+\infty} {\mathrm{lim}t}\underset{\mathrm{k}=\mathrm{0}} {\overset{\infty} {\sum}}\frac{\left(−\mathrm{1}\right)^{\mathrm{k}} }{\:\sqrt{\mathrm{k}^{\mathrm{2}} +\mathrm{t}^{\mathrm{2}} }}=? \\ $$