Prove the lemma about existence of additive inverses in Zn. (lemma- theres a (-x) in Zn such that x+(-x)[0]n(-x)+x.)?
In Zn (-x) is also known as n-x for x positive. In Zn, 0+0 0 and 0 is the additive inverse of 0, 1 +(n-1) 0 in Zn and n-1 is the additive inverse of 1, 2 +(n-2) 0, etc.: k+(n-k) 0
