If A=
, then A-1=?
-1= 
adj A --------- 1
= 3 x 2 – (1) x (-1)
7
C11 = 3 C12 = -1
C21= 1 C22 = 2
Cofactor matrix A = 
Adj A =
’
= 
Putting in 1
A-1= 
= 
1
If A=, then A-1=?
-1= adj A --------- 1
= 3 x 2 – (1) x (-1)
7
C11 = 3 C12 = -1
C21= 1 C22 = 2
Cofactor matrix A =
Adj A =’
=
Putting in 1
A-1=
=