Question:
Find the inverse of each of the matrices (if it exists).
$\left[\begin{array}{rr}2 & -2 \\ 4 & 3\end{array}\right]$
Solution:
Let $A=\left[\begin{array}{rr}2 & -2 \\ 4 & 3\end{array}\right]$.
we have.
$|A|=6+8=14$
Now,
$A_{11}=3, A_{12}=-4, A_{21}=2, A_{22}=2$
$\therefore \operatorname{adj} A=\left[\begin{array}{ll}3 & 2 \\ -4 & 2\end{array}\right]$
$\therefore A^{-1}=\frac{1}{|A|}$ adjA $=\frac{1}{14}\left[\begin{array}{ll}3 & 2 \\ -4 & 2\end{array}\right]$