TeX джерело:

AA^{-1}\;=\;\left(\begin{array}{rrr}1&2&1\\3&0&2\\2&1&4\end{array}\right)\;\left(\begin{array}{rrr}\frac{2}{15}&\frac{7}{15}&-\frac{4}{15}\\ \frac{8}{15}&-\frac{2}{15}&-\frac{1}{15}\\ -\frac{3}{15}&-\frac{3}{15}&\frac{6}{15} \end{array}\right)\,=\,\left(\begin{array}{rrr}1&0&0\\0&1&0\\0&0&1\end{array}\right).