## Precalculus (6th Edition) Blitzer

$\dfrac{9}{4}$
The general formula to find the sum of an infinite Geometric series is given as: $S_{n}=\dfrac{a_1}{(1-r)}$ and $r=\dfrac{a_2}{a_1}=\dfrac{-1}{3}=\dfrac{-1}{3}$ Now, $S_{n}=\dfrac{a_1}{(1-r)}=\dfrac{3}{1-(-\dfrac{1}{3})}$ Our answer is: $S_{n}=\dfrac{3}{3/4}=\dfrac{9}{4}$