A =

A² =

=

Now, A² = λA – 2I

= λA = A² + 2I

=

= λ

=

= = 3 or λ = 1

So, A² = A – 2I

Multiply by A ^{– 1} both sides

= A.A. A ^{– 1} = A. A ^{– 1} – 2I. A ^{– 1} = 0

= 2A ^{– 1} =

Hence, A ^{– 1} =