Hi guys, I have quastion about groups: G is abelian group with an identity element "e". If xx=e then x=e. Is it true or false? I was thinking and my feeling is that it's true but I just can't prove it. I started with: (*) ae=ea=a (*) aa^-1 = a^-1 a = e those from the definition of Group and now the assuming: aa=e then: aa^-1 = e = aa a=a^-1 ==> a^-1 a = aa = e that's all i got. Is anyone can halp? thank you!