Solution:
Here the determinant is compared so we need to take determinant both sides then find $\mathrm{x}$.
$\begin{array}{l}
12 x+14=32-42 \\
\Rightarrow 12 x=-10-14 \\
\Rightarrow 12 x=-24 \\
\Rightarrow x=-2
\end{array}$
If $\left|\begin{array}{cc}3 x & 7 \\ -2 & 4\end{array}\right|=\left|\begin{array}{ll}8 & 7 \\ 6 & 4\end{array}\right|$, write the value of $x$.
If $\left|\begin{array}{cc}3 x & 7 \\ -2 & 4\end{array}\right|=\left|\begin{array}{ll}8 & 7 \\ 6 & 4\end{array}\right|$, write the value of $x$.