Compute
\[\begin{pmatrix} 3a^2 - 3 & 3a \\ 2a^2 - a - 2 & 2a - 1 \end{pmatrix} \begin{pmatrix} -1 & -3a - 2 \\ a & 3a^2 + 2a - 3 \end{pmatrix}.\]
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Compute
\[\begin{pmatrix} 3a^2 - 3 & 3a \\ 2a^2 - a - 2 & 2a - 1 \end{pmatrix} \begin{pmatrix} -1 & -3a - 2 \\ a & 3a^2 + 2a - 3 \end{pmatrix}.\]
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
\begin{pmatrix} 3 & 6 \\ 2 & 7 \end{pmatrix}
Compute
\[\begin{pmatrix} 3a^2 - 3 & 3a \\ 2a^2 - a - 2 & 2a - 1 \end{pmatrix} \begin{pmatrix} -1 & -3a - 2 \\ a & 3a^2 + 2a - 3 \end{pmatrix}.\]
train