## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$\bf{diverges \ series }$
The sum of a convergent infinite geometric series is given by the formula: $S_{\infty}=\dfrac{a_1}{1-r}$ and a geometric series converges if $|r| \lt 1$ and an infinite geometric series diverges if $|r| \gt 1$. Therefore, our missing expression in the given statement is: $\bf{diverges \ series }$