Question

If $A=\begin{bmatrix} a & b\\\[0.3em] c & -a \\\[0.3em] \end{bmatrix}$is a matrix such that $A^2=I$, where $I$ is an identity matrix, then which of the following is TRUE?

• A. $1+a^2+bc=0$
• B. $1-a^2+bc=0$
• C. $1-a^2-bc=0$
• D. $1+a^2-bc=0$

Answer 1

Answer: (C)

$1-a^2-bc=0$

Answer 2

The correct option is (C): $1-a^2-bc=0$.