Question

Let $A$ and $B$ are two square matrices such that $AB=A$ and $BA=B,$ then $A^2$ equals to:

• A. B
• B. A
• C. $I$
• D. 0
• E. $A^{-1}$

Answer 1

Answer: (B)

$A^2=A.A=AB.A$ $=A.BA=AB=A$