For instance,
If  
1
0
3
0
A
, B
0
2
0
4




=
=








, then AB = BA = 
3
0
0
8






Observe that multiplication of diagonal matrices of same order will be commutative Zero matrix as the product of two non zero matrices
We know that, for real numbers a, b if ab = 0, then either a = 0 or b = 0 This need
not be true for matrices, we will observe this through an example Example 15 Find AB, if 
0
1
A
0
−2


= 



 and 
3
5
B
0
0


= 


