Final answer:
The common ratio of the given geometric series is -2.
Step-by-step explanation:
In the given geometric series (-2)n - 1 7n, we need to find the common ratio. A geometric series is a sequence of numbers where each term is found by multiplying the previous term by a fixed, non-zero number called the common ratio. In this series, each term is obtained by multiplying the previous term by -2. Hence, the common ratio is -2.