Respostas

2014-04-14T11:01:50-03:00
A)
3  \left[\begin{array}{cc}3&2\\-1&0\\\end{array}\right] -6\left[\begin{array}{cc}1&2\\4&0\\\end{array}\right] \\
  \left[\begin{array}{cc}9&6\\-3&0\\\end{array}\right] -\left[\begin{array}{cc}6&12\\24&0\\\end{array}\right] \\
  \left[\begin{array}{cc}9-6&6-12\\-3-24&0-0\\\end{array}\right] \\
  \left[\begin{array}{cc}3&-6\\-27&0\\\end{array}\right]

b)
Como o número de colunas de A é igual ao número de linhas de B, teremos:
 \left[\begin{array}{cc}3&2\\-1&0\\\end{array}\right] .\left[\begin{array}{cc}1&2\\4&0\\\end{array}\right] \\
\left[\begin{array}{cc}3.1+2.4&3.2+2.0\\-1.1+0.4&-1.2+0.0\\\end{array}\right] \\
\left[\begin{array}{cc}9&6\\-1&-2\\\end{array}\right]