# How do you find the inverse of A=((1, 2), (1, 3))?

$= \left[\begin{matrix}3 & - 2 \\ - 1 & 1\end{matrix}\right]$
${A}^{- 1} = \frac{1}{\det \left(A\right)} \cdot a \mathrm{dj} \left(a\right)$
$= \frac{1}{1 \left(3\right) - 1 \left(2\right)} \left[\begin{matrix}3 & - 2 \\ - 1 & 1\end{matrix}\right]$
$= \left[\begin{matrix}3 & - 2 \\ - 1 & 1\end{matrix}\right]$