## Precalculus (6th Edition) Blitzer

$2049$
The general formula to find the nth partial sum of a Geometric sequence is given as: $S_{n}=\dfrac{a(1-r^n)}{(1-r)}$ $r=\dfrac{a_2}{a_1}=\dfrac{-6}{3}=-2$ and $n=11$ Now, $S_{11}=\dfrac{3(1-(-2)^{11})}{(1-(-2))}=3 \times \dfrac{2049}{3}$ Our answer is: $S_{11}=2049$