Sejam as matrizes $A=\left(\begin{array}{cc}2& 4\\ 0& 4\end{array}\right),B=\left(\begin{array}{cc}1& 2\\ 0& 4\end{array}\right),Z=\left(\begin{array}{cc}0& 0\\ 0& 0\end{array}\right),I=\left(\begin{array}{cc}1& 0\\ 0& 1\end{array}\right)$ então temos que: