Question

If A is a square matrix such that $A^2 = I$, then $A^{-1}$ is equal to

• A. I
• B. O
• C. A
• D. A + I

Answer 1

Answer: (C)

A

Answer 2

$A^{2} =I \Rightarrow AA =I \Rightarrow A^{-1} \left(AA\right)=A^{-1} I$ $\Rightarrow A = A^{-1}$