Answer
$0$
Work Step by Step
The determinant of a $2\times2$ matrix $A=\begin{bmatrix}a & b\\c&d
\end{bmatrix}$ is given by $ad-bc.$ Hence, the determinant of the given matrix, $
\begin{bmatrix}
6&2\\-6&-2
\end{bmatrix}$ is
\begin{align*}
&
6(-2)-(-6)(2)
\\&=
-12+12
\\&=
0
.\end{align*}