## Kris5 2 years ago Please help...Find the sum of the first six terms of the series: -96,144,-216,324,...

1. mathmate

The rule is $$a_{n+1} = -1.5 a_n$$ with $$a_0=-96 , and r=-1.5$$ The partial sum is $$a_0\frac{1-r^n}{1-r}=(-96)\frac{1-(-1.5)^6}{1-(-1.5)}$$

2. Kris5

oohh okay thank you

3. Kris5

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4. mathmate

yw!