+ ain bnk = 
1
n
ij
jk
j
a b
=∑ The matrix C = [cik]m × p is the product of A and B For example, if 
1
1
2
C
0
−3 4


= 



 and 
2
17
D
1
5
4




= −



−


 , then the product CD is defined
Rationalised 2023-24
 52
MATHEMATICS
and is given by 
2
7
1
1
2
CD
1
1
0
3
4
5
4


−

 

=
−

 


 
−

 This is a 2 × 2  matrix in which each
entry is the sum of the products across some row of C with the corresponding entries
down some column of D