In other words, D = A – B = A + (–1) B, that is sum of the matrix
A and the matrix – B Example 7 If 
1
2
3
3
1
3
A
and B
2
3
1
1
0
2
−




=
=




−




, then find 2A – B Solution We have
2A – B = 2 1
2
3
2
3 1
3
1
3
1
0
2



 −
−
−




=
2
4
6
3 1
3
4
6
2
1
0
2
−
−




+



−




=
2
3
4
1
6
3
1
5
3
4
1
6
0
2
2
5
6
0
−
+
−
−




=




+
+
−




3 4