Answer:
Option c
[tex]-7A-6B=\left(\begin{array}{ccc}40&-106&-32\\-46&43&25\\82&-62&-18\end{array}\right)[/tex]
Step-by-step explanation:
First multiply matrix A by -7.
Then multiply the matrix B by -6.
When multiplying a matrix by a number x you must multiply each element of the matrix by x.
Then we perform operation -7A
[tex]-7\left(\begin{array}{ccc}-10&10&8\\-2&-1&5\\-4&8&-6\end{array}\right)=\left(\begin{array}{ccc}70&-70&-56\\14&7&-35\\28&-56&42\end{array}\right)[/tex]
Now we perform operation -6B
[tex]-6\left(\begin{array}{ccc}5&6&-4\\10&-6&-10\\-9&1&10\end{array}\right)=\left(\begin{array}{ccc}-30&-36&24\\-60&36&60\\54&-6&-60\end{array}\right)[/tex]
Now we add the resulting matrices
[tex]\left(\begin{array}{ccc}70&-70&-56\\14&7&-35\\28&-56&42\end{array}\right)+\left(\begin{array}{ccc}-30&-36&24\\-60&36&60\\54&-6&-60\end{array}\right)=\left(\begin{array}{ccc}40&-106&-32\\-46&43&25\\82&-62&-18\end{array}\right)[/tex]
