Answer:
Option c
Step-by-step explanation:
We have two matrices, matrix A and matrix B.
Before doing the addition of matrices, we must multiply the matrix A by the scalar -7 and then multiply the matrix B by the scalar -6.
The multiplication of a matrix A by a scalar c, is done by multiplying all the elements of matrix A by the value c.
So
[tex]-7A = \left[\begin{array}{ccc}70&-70&-56\\14&7&-35\\28&-56&42\end{array}\right]\\\\\\-6B =\left[\begin{array}{ccc}-30&-36&24\\-60&36&60\\54&-6&-60\end{array}\right][/tex]
Now we add both matrices.
The sum of the matrices is done by adding each term [tex]a_{mn}[/tex] with each term [tex]b_{mn}[/tex]
For example: (70 - 40) , (-70 + (-36)), ...,
Then:
[tex]-7A + (-6B) = \left[\begin{array}{ccc}40&-106&-32\\-46&43&25\\82&-62&-18\end{array}\right][/tex]
