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To find common ratio, simply divide one term by its predecessor.
\nTo find the $n$th term, multiply the first term a by the common ratio r to the power of n-1, ie ${a}{r^{n-1}}$
\nFormula for the sum of the first $n$ terms is where $r$ is the common ratio and $a$ is the first term
\nFormula for the infinite sum, providing $| r |<1$, is C
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\n$\\var{t1}$+$\\simplify{{t1}*{r}}$+$\\simplify{{t1}*{{r}^2}}$+$\\simplify{{t1}*{{r}^3}}$+...
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