## Thomas' Calculus 13th Edition

=$5\Sigma_{k=1} (-1)^{k} \frac {k}{5}$
-Put k=1,2,3,4,5 into $\frac {k}{5}$ and it will be equal -- 1-$\frac{1}{5}$+$\frac{2}{5}$+$\frac{3}{5}$+$\frac{4}{5}$+$\frac{5}{5}$ --SIgma Notation Will be =$5\Sigma_{k=1} (-1)^{k} \frac {k}{5}$