|A| =

= 1(16 – 9) – 3(4 – 3) + 3(3 – 4)

= 7 – 3 – 3

= 1

Hence, A ^{– 1} exists

Cofactors of A are:

C₁₁ = 7 C₂₁ = – 3 C₃₁ = – 3

C₁₂ = – 1 C₂₂ = – 1 C₃₂ = 0

C₁₃ = – 1 C₂₃ = 0 C₃₃ = 1

adj A =

=

So, adj A =

Now, A ^{– 1} =

Also, A ^{– 1}.A =

=

=

Hence, A ^{– 1}.A = I