matrix question?

Question

if A^2=A what can you say detA

Answer 1

if A^2=A
det A^2=DetA
detA*A=DetA
DetA*DetA=DetA by product of det marices |AB|=|A||B|
detA(detA-1)=0
Det A=0
and DetA=1
good luck

Answer 2

If A^2 = A, then A is idempotent, and so the determinant is equal to 1 (assuming, of course, that A is not the zero matrix).

Answer 3

If it bleeds, we can kill it