Example 25 Let 
2
1
5
2
2
5
A
, B
, C
3
4
7
4
3
8
−






=
=
=











 Find a matrix D such that
CD – AB = O Solution Since A, B, C are all square matrices of order 2, and CD – AB is well
defined, D must be a square matrix of order 2 Let
D = a
b
c
d





