Answer
0
Work Step by Step
We evaluate the sum:
$\sum_{j=1}^{100}(-1)^{j}=(-1)^{1}+(-1)^{2}+(-1)^{3}+(-1)^{4}+(-1)^{5}+...+(-1)^{99}+(-1)^{100}=-1+1-1+1-1+...-1+1=0$
(Since we have an even number of terms, the $+1$ and $-1$ cancel out.)
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