One of my favorite formulas is the closed-form of the geometric series.
I am amazed by its ubiquity: whether we are solving basic problems or pushing the boundaries of science, the geometric series often makes an appearance.
Here is how to derive it from first principles:
Let’s start with the basics: like any other series, the geometric series is the limit of its partial sums.
Our task is to find that limit.
There is an issue: the number of terms depends on N.