91Ó°ÊÓ

Let A and B be two $m×n$matrices, then following operations are defined:

• Matrix Addition- $A+B$is an $m×n$matrix in which each element is the sum of the corresponding elements of A and B
• Matrix Subtraction- $A-B$is an $m×n$matrix in which each element is the difference of the corresponding elements of A and B
• Scalar Multiplication- The product of a scalar k with $m×n$matrix is an $m×n$matrix in which each element equals k times the corresponding elements of the original matrix.

First matrix operation applied in given expression is scalar multiplication. Multiply given matrices with scalars as shown below

$4\left[\begin{array}{ccc}3& 4& −7\\ 6& −9& −2\\ 3& 1& 3\end{array}\right]−\left[\begin{array}{ccc}−8& 6& −4\\ −7& 10& 1\\ −2& 1& 5\end{array}\right]=\left[\begin{array}{ccc}12& 16& −28\\ 24& −36& −8\\ −12& 4& 12\end{array}\right]−\left[\begin{array}{ccc}−8& 6& −4\\ −7& 10& 1\\ −2& 1& 5\end{array}\right]$

As both the matrices are of same dimension, so apply matrix subtraction to get,

$\begin{array}{c}\left[\begin{array}{ccc}12& 16& −28\\ 24& −36& −8\\ −12& 4& 12\end{array}\right]−\left[\begin{array}{ccc}−8& 6& −4\\ −7& 10& 1\\ −2& 1& 5\end{array}\right]=\left[\begin{array}{ccc}12+8& 16−6& −28+4\\ 24+7& −36−10& −8−1\\ −12+2& 4−1& 12−5\end{array}\right]\\ =\left[\begin{array}{ccc}20& 10& −24\\ 31& −46& −9\\ −10& 3& 7\end{array}\right]\end{array}$