Answer
$M_{11}=4$
$M_{12}=3$
$M_{13}=2$
$M_{14}=1$
$C_{11}=4$
$C_{12}=-3$
$C_{13}=-2$
$C_{14}=1$
Work Step by Step
$ \begin{bmatrix}
1 &2 \\
3& 4\\
\end{bmatrix} $
Minor $M_{ij}$of the entry $a_{ij}$ is the determinant of
the matrix obtained by deleting the i-th row and j-th column of the matrix.
To get $M_{11}$ we delete the second row and the second column and we get $M_{11}=4$. Use this method analogically to calculate $M_{12}$, $M_{21}$ and $M_{22}$.
$M_{12}=3$
$M_{21}=2$
$M_{22}=1$
To calculate the cofactors, use the cofactor definition: $C_{ij}=(-1)^{ij}\times M_{ij}$
$C_{11}=4$
$C_{12}=-3$
$C_{21}=-2$
$C_{22}=1$
