# matrix invers

for 2x2

\\[ A^{-1} = \frac{1}{(a \cdot d) - (b \cdot c)} \begin{bmatrix} d & -b & \newline -c & a \end{bmatrix}\\]

for 3x3
\\[ A^{-1} = \frac{1}{\det A} \text{adj } A \\]

sequence for 3x3 matrix

- search minor matrices (tutup angka)
- then calculate cofactor (plus minus)
- matrix adjoin (transpose of cofactor matrix)