Answer
-18
Work Step by Step
We use Cramer's rule to find the determinant of the matrix. Doing this, we obtain:
$$ \det \begin{pmatrix}2&4&-2\\ 1&0&2\\ 0&1&3\end{pmatrix}\\ 2\cdot \det \begin{pmatrix}0&2\\ 1&3\end{pmatrix}-4\cdot \det \begin{pmatrix}1&2\\ 0&3\end{pmatrix}-2\cdot \det \begin{pmatrix}1&0\\ 0&1\end{pmatrix}\\ -18$$
