Precalculus Examples

$\sum_{K = 2}^{6} {(- 1)}^{K} (7 - K) K$

Step 1

Expand the series for each value of $K$ .

${(- 1)}^{2} (7 - 1 \cdot 2) \cdot 2 + {(- 1)}^{3} (7 - 1 \cdot 3) \cdot 3 + {(- 1)}^{4} (7 - 1 \cdot 4) \cdot 4 + \dots + {(- 1)}^{6} (7 - 1 \cdot 6) \cdot 6$

Step 2

Simplify the expanded form.

$6$