Chapter 12 - Sequences; Induction; the Binomial Theorem - 12.3 Geometric Sequences; Geometric Series - 12.3 Assess Your Understanding - Page 825: 59

diverges

An infinite geometric series converges if and only if $|r|\lt1$, where $r$ is the common ratio. If it converges, then it equals $\frac{a_1}{1-r}$ where $a_1$ is the first term. The common ratio is the quotient of two consecutive terms: $r=\frac{a_2}{a_1}=\dfrac{12}{8}=\frac{3}{2}$. $|\frac{3}{2}|=\frac{3}{2}\gt1$, thus it diverges.