Question

Find co-factors of elements of the matrices $\left[\begin{array}{cc}-1& 2\\ -3& 4\end{array}\right]$

Answer 1

$\left[\begin{array}{cc}-1& 2\\ -3& 4\end{array}\right]$

co-factor of $-1$ and $4$ is $4$ and $-1$

minor of 2 is -3 and co factor is $3$

minor of -3 is 2 and co factor is $-2$

$\therefore$ co factor matrix $\Rightarrow$ $\left[\begin{array}{cc}4& 3\\ -2& -1\end{array}\right]$