Answer
geometric,
$r=\frac{1}{2}$
$S_n=6(1-(\frac{1}{2})^n)$
Work Step by Step
1. Based on the given sequence, we can determine it is geometric,
2. We can find the common ratio as $r=\frac{s_2}{s_1}=\frac{3/2}{3}=\frac{1}{2}$
3. We can find the sum of the first n terms as $S_n=\frac{s_1(r^n-1)}{r-1}=\frac{3((1/2)^n-1)}{1/2-1}=6(1-(\frac{1}{2})^n)$
