Theorem negeqi

Description: Equality inference for negatives. (Contributed by NM, 14-Feb-1995)

	Ref	Expression
Hypothesis	negeqi.1	⊢ 𝐴 = 𝐵
Assertion	negeqi	⊢ - 𝐴 = - 𝐵

Proof

Step	Hyp	Ref	Expression
1		negeqi.1	⊢ 𝐴 = 𝐵
2		negeq	⊢ ( 𝐴 = 𝐵 → - 𝐴 = - 𝐵 )
3	1 2	ax-mp	⊢ - 𝐴 = - 𝐵