## Calculus with Applications (10th Edition)

We know that if a geometric series has a first term $a$ and a common ratio of $r$, the nth term can be expressed as $a_n=a\cdot r^{n-1}$ Hence here: $a_1=2\cdot 3^{1-1}=2\cdot 3^0=2$ $a_2=2\cdot 3^{2-1}=2\cdot 3^1=6$ $a_3=2\cdot 3^{3-1}=2\cdot 3^2=18$ $a_4=2\cdot 3^{4-1}=2\cdot 3^3=54$