For the following pairs of matrices verify that (AB)–1 = B – 1A – 1:
A=
A = 
, |A| = 1
Then, adj A = 
A – 1 = 
B = 
, |B| = – 10
Then, adj B = 
B – 1 = 
Also, A.B = 
AB = 
|AB| = 936 – 946 = – 10
Adj(AB) = 
(AB) – 1 = 
Now B – 1A – 1 = 
= 
= 
Hence, (AB) – 1 = B – 1 A – 1
10