Respuesta :

[tex] -9\left[\begin{array}{cc}7&-4\\-3&0\ \end{array}\right] = \left[\begin{array}{cc}7\times -9&-4\times -9\\-3\times -9&0\times -9\ \end{array}\right] = \left[\begin{array}{cc}-63&36\\27&0\ \end{array}\right][/tex]