Question

Find -7a-6B (Picture provided)

Answer 1

Answer:

Option c

$-7A-6B=\left(\begin{array}{ccc}40&-106&-32\\-46&43&25\\82&-62&-18\end{array}\right)$

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

$-7\left(\begin{array}{ccc}-10&10&8\\-2&-1&5\\-4&8&-6\end{array}\right)=\left(\begin{array}{ccc}70&-70&-56\\14&7&-35\\28&-56&42\end{array}\right)$

Now we perform operation -6B

$-6\left(\begin{array}{ccc}5&6&-4\\10&-6&-10\\-9&1&10\end{array}\right)=\left(\begin{array}{ccc}-30&-36&24\\-60&36&60\\54&-6&-60\end{array}\right)$

Now we add the resulting matrices

$\left(\begin{array}{ccc}70&-70&-56\\14&7&-35\\28&-56&42\end{array}\right)+\left(\begin{array}{ccc}-30&-36&24\\-60&36&60\\54&-6&-60\end{array}\right)=\left(\begin{array}{ccc}40&-106&-32\\-46&43&25\\82&-62&-18\end{array}\right)$