If 
show that A2 = I.
Given : 
Matrix A is of order 3 
3
To show : A2 = I
Formula used : 
If A is a matrix of order a 
b and B is a matrix of order c 
d ,then matrix AB exists and is of order a 
d ,if and only if b = c
A2 = 
A2 = 
A2 = 
= 
A2 = I = 
1