Answer
$682$
Work Step by Step
We have to determine the sum:
$\sum_{k=1}^{10} (-2)^k$
Consider the geometric sequence:
$a_1=(-2)^1=-2$
$r=-2$
Compute the sum of the first 10 terms:
$S_n=a_1\dfrac{1-r^n}{1-r}$
$n=10$
$\sum_{k=1}^{10} (-2)^k=S_7=(-2)\cdot\dfrac{1-(-2)^{10}}{1-(-2)}$
$=-2\cdot \dfrac{1-1024}{3}=-2\cdot\dfrac{-1023}{3}=2(341)=682$