Respostas

2013-09-09T21:16:06-03:00
  \left[\begin{array}{ccc}1&2&0\\3&-1&2\end{array}\right] .   \left[\begin{array}{ccc}2&0&\\1&-3\\-1&2\end{array}\right] =

  \left[\begin{array}{ccc}2+2+0&0+6+0\\6-1-2&0+3+4\end{array}\right] =

  \left[\begin{array}{ccc}4&6\\3&7\end{array}\right]

lembrando que a multiplicação de matrizes e da horizontal pela a vertical.

se for pra resolver e assim.