First, we can write the system of equations in matrix form:
$$\begin{pmatrix}6 & 12 \\ 4 & 7\end{pmatrix}\begin{pmatrix}x \\ y\end{pmatrix}=\begin{pmatrix}33 \\ 20\end{pmatrix}$$
The determinant of the coefficient matrix is:
$$\begin{vmatrix}6 & 12 \\ 4 &
Show more…