## Algebra 2 (1st Edition)

$a_n=144\cdot(\frac{1}{3})^{n-1}$
The nth term of a geometric series can be obtained by the following formula: $a_n=a_1\cdot r^{n-1}$, where $a_1$ is the first term and $r$ is the common ratio. $a_3=a_1\cdot r^2$, thus $r=\frac{1}{3}$ Here the common ratio is $r=\frac{1}{3}$ and $a_1=144$. Hence here $a_n=144\cdot(\frac{1}{3})^{n-1}$