Precalculus Examples

$\sum_{j = 1}^{6} {(- 1)}^{j + 1} j$

Step 1

Expand the series for each value of $j$ .

${(- 1)}^{1 + 1} \cdot 1 + {(- 1)}^{2 + 1} \cdot 2 + {(- 1)}^{3 + 1} \cdot 3 + \dots + {(- 1)}^{6 + 1} \cdot 6$

Step 2

Simplify the expanded form.

$- 3$