Sum of the First n Terms of a Geometric Sequence
Prerequisite Knowledge: Before diving in, make sure you're comfortable with geometric sequences — sequences where each term is found by multiplying the previous term by a constant ratio $r$.
1. What Is a Geometric Series?
A geometric sequence looks like this:
$a, \; ar, \; ar^2, \; ar^3, \; \ldots, \; ar^{n-1}$
where $a$ is the first term and $r$ is the common ratio.