Answer
See below.
Work Step by Step
The sum of a geometric sequence until $n$ can be obtained by the formula $S_n=a_1(\frac{1-r^n}{1-r})$ where $a_1=-2$ is the first term and $r=-2$ is the common ratio. Hence here the sum is: $S_n=-2(\frac{1-(-2)^{10}}{1-(-2)})=682$.
