Practice problem
Let an=(−2)na_n = (-2)^nan=(−2)n for all n≥0n \ge 0n≥0. Find the value of rrr which satisfies ∑n=18an=∑n=14rn2\sum_{n=1}^8 a_n = \sum_{n=1}^4 \frac{r^n}{2}n=1∑8an=n=1∑42rn
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Type a concept, like “slope” or “photosynthesis”.
