Question

A is a square matrix such that $A^2=A$, then dot (A) is equal to

Answer 1

$A^2=A$ A can be a zero matrix $\begin{array}{c}IfA=0|A|=0\\ IfA=1|A|=1\end{array}\}\to dot\left(A\right)=0or1$
$\therefore A^2–A=0$
A(A-I)=0 identity matrix
$\therefore$ A=0 or A=1