TeX джерело:

AA^{-1}\;=\;\left(\begin{array}{rr}3&4\\1&5\end{array}\right)\;\left(\begin{array}{rr}\frac{5}{11}\,&\,-\frac{4}{11}\\-\frac{1}{11}\,&\frac{3}{11} \end{array}\right)=\left(\begin{array}{rr}3 \cdot \frac{5}{11}-4\cdot\frac{1}{11}\, &\,3 \cdot (-\frac{4}{11})+4\cdot\frac{3}{11}\\1 \cdot \frac{5}{11}-5\cdot\frac{1}{11}\, &\,1 \cdot (-\frac{4}{11})+5\cdot\frac{3}{11}\end{array}\right)=\left(\begin{array}{rr}1&0\\0&1\end{array}\right)=E