Theorem eqnegi

Description: A number equal to its negative is zero. (Contributed by NM, 29-May-1999)

	Ref	Expression
Hypothesis	divclz.1	|- A e. CC
Assertion	eqnegi	|- ( A = -u A <-> A = 0 )

Proof

Step	Hyp	Ref	Expression
1		divclz.1	|- A e. CC
2		eqneg	|- ( A e. CC -> ( A = -u A <-> A = 0 ) )
3	1 2	ax-mp	|- ( A = -u A <-> A = 0 )