Sum of Geometric Sequences

Here are two useful formulas that are presented in a pretty way. Thank you GitHub for the math LaTeX rendering.

Sum of a Finite Geometric Series

$S_n=\sum_{i=1}^{n}a_ir^{i-1}=a_1\frac{r^n-1}{r-1}$ $S_n=a_1\frac{r^n-1}{r-1}=a_1\frac{1-r^n}{1-r}$

$S=\sum_{i=0}^{\infty}a_ir^i=\frac{a_1}{1-r}$

2021-Dec-18