Given: A is a square matrix, I is an identity matrix of the same order, and A2=A.
Expand (2I+A)2:
(2I+A)2=(2I+A)(2I+A)
=2I⋅2I+2I⋅A+A⋅2I+A⋅A
=4I+2A+2A+A2
=4I+4A+A2
Using A2=A:
=4I+4A+A
=4I+5A
Calculate the final expression:
(2I+A)2−5A=4I+5A−5A
=4I
Final Answer: 4I