Given.

We need to find A² – 5A + 4I.

We know A² = A × A.

Now, we evaluate –5A = –5 × A.

Finally, matrix 4I = 4 × I.

The given expression is A² – 5A + 4I.

Given that A² – 5A + 4I + X = O

⇒ X = – (A² – 5A + 4I)

Thus, and