Sum of the minor and the cofactor of the element 6 in the determinant $\left|\begin{array}{lll}2 & 3 & 1 \\ 4 & 5 & 6 \\ 7 & 8 & 9\end{array}\right|$ is:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) - 0
for element 6
Minor $M_{23}=\begin{vmatrix}2&3\\7&8\end{vmatrix}$
Cofactor $C_{23}=(-1)^{(2+3)}\begin{vmatrix}2&3\\7&8\end{vmatrix}$
$C_{23}=-M_{23}$
$M_{23}+C_{23}=0$