# Math Help - Series & Sequences

1. ## Series & Sequences

how do you find the sum of an infinite series?

2. Depending on the series, there are tricks sometimes ... often not. A well-known case are the geometric series where you can multiply by a factor of (x-1) and everything cancel in a nice way. It only converges for $1 \geq r \geq -1$ though.
$\sum_{i=0}^n x^i = \frac{1-x^{n+1}}{1-x}$

3. $\frac{a}{1-r}$

Where a = first term in the sequence
r = common ratio $(-1

4. Originally Posted by Lupin
$\frac{a}{1-r}$

Where a = first term in the sequence
r = common ratio $(-1
It should be said that this the sum of an infinite geometric series.

5. Originally Posted by >_<SHY_GUY>_<
how do you find the sum of an infinite series?