[tex]\bf a_1=-2\qquad a_n=3\cdot a_{n-1}\qquad
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term}\\
r=\textit{common ratio}\\
-------\\
n=6\\
a_1=-2\\
r=3
\end{cases}
\\\\\\
a_n=a_1\cdot r^{n-1}\implies a_6=(-2)(3^{6-1})[/tex]
notice, the notation is just saying, that 3 * "the previous term, or n-1" is the next term, thus the common ratio, or multiplier is 3
