Question

If the value of determinant $\left|\begin{array}{cc}m& 6\\ -5& 4\end{array}\right|$ is $58$, then find the value of $m$.

Answer 1

A] Given $\left|\begin{array}{cc}m& 6\\ -5& 4\end{array}\right|$ is $58$,

$=4m-(-5)\times 6=58$

$=4m+30=58$

$=4m=28$ $\therefore m=7$