Question Number 31946 by gunawan last updated on 17/Mar/18
$$\mathrm{Calculate}\:\underset{{j}\leqslant{k}\leqslant{i}} {\Sigma}\:\left(−\mathrm{1}\right)^{{k}} \begin{pmatrix}{{i}}\\{{k}}\end{pmatrix}\begin{pmatrix}{{k}}\\{{j}}\end{pmatrix} \\ $$