Очень нужно , помогите с математикой

Решите задачу:

$11. C= \left(\begin{array}{cc}1&4\\3&6\end{array}\right) \left(\begin{array}{cc}7&-1\\-6&1\end{array}\right) = \left(\begin{array}{cc}7-24&-1+4\\21-36&-3+6\end{array}\right) = \left(\begin{array}{cc}-17&3\\-15&3\end{array}\right)$
$12. C= 2\left(\begin{array}{cc}1&4\\3&6\end{array}\right) +3 \left(\begin{array}{cc}7&-1\\-6&1\end{array}\right) = \left(\begin{array}{cc}2&8\\6&12\end{array}\right) +\left(\begin{array}{cc}21&-3\\-18&3\end{array}\right)$ $C=\left(\begin{array}{cc}2+21&8-3\\6-18&12+3\end{array}\right)=\left(\begin{array}{cc}23&5\\-12&15\end{array}\right)$