้่กๅ
https://gyazo.com/2e06f7a90aea7ceab7cffed20dfde236
$ A^{-1} = \frac{1}{ad-bc} \left( \begin {array}{} d & -b \\ -c & a \end {array} \right)
$ A = \left( \begin{array}{cc} a & b \\ c & d \end{array} \right)
ใจใใ