A Geometric [[Series]] is a type of series where each element is equal to a constant times the previous element. $\huge x_{n} = p+ar^{n} $ For $p=0$ and $a=1$, we get the [[Summation|summations]]: $\huge \begin{align} S_{n}&=\frac{{1- z^{n}}}{1-z} \\ S &= \frac{1}{1-z} \end{align} $