Answer:
Option a
[tex]6A-8B=\left(\begin{array}{ccc}56&50&-14\\-126&92&62\\-78&26&2\end{array}\right)[/tex]
Step-by-step explanation:
First multiply matrix A by 6.
Then multiply the matrix B by -8.
When multiplying a matrix by a number x you must multiply each element of the matrix by x.
Then we perform operation 6A
[tex]6\left(\begin{array}{ccc}-4&-1&-9\\-9&6&9\\-1&-1&3\end{array}\right)=\left(\begin{array}{ccc}-24&-6&-54\\-54&36&54\\-6&-6&18\end{array}\right)[/tex]
[tex]-8\left(\begin{array}{ccc}-10&-7&-5\\9&-7&-1\\9&-4&2\end{array}\right)=\left(\begin{array}{ccc}80&56&40\\-72&56&8\\-72&32&-16\end{array}\right)[/tex]
Now we add the resulting matrices
[tex]\left(\begin{array}{ccc}-24&-6&-54\\-54&36&54\\-6&-6&18\end{array}\right)+\left(\begin{array}{ccc}80&56&40\\-72&56&8\\-72&32&-16\end{array}\right)=\left(\begin{array}{ccc}56&50&-14\\-126&92&62\\-78&26&2\end{array}\right)[/tex]
