## anonymous 3 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. anonymous

oohh okay thank you

3. anonymous

:]

4. mathmate

yw!