# Geometric logic

1. Oct 26, 2006

### L²Cc

do you have an explanation to why sometimes the general term formula for geometric sequence is not raised to n-1 but to simply n?

2. Oct 26, 2006

because you could have $$\sum_{n=0}^{\infty} ar^{n}$$ or $$\sum_{n=1}^{\infty} ar^{n-1}$$

Or $$\sum_{n=k}^{\infty} ar^{n-k}$$

Last edited: Oct 26, 2006
3. Oct 26, 2006

### L²Cc

oh ok...so from what I understood, if the sequence starts at zero then the formula raised to n because if it was n-1 then it will read -1, right?

4. Oct 26, 2006