Theorem neg11d

Description: If the difference between two numbers is zero, they are equal. (Contributed by Mario Carneiro, 27-May-2016)

	Ref	Expression
Hypotheses	negidd.1	⊢ ( 𝜑 → 𝐴 ∈ ℂ )
	pncand.2	⊢ ( 𝜑 → 𝐵 ∈ ℂ )
	neg11d.3	⊢ ( 𝜑 → - 𝐴 = - 𝐵 )
Assertion	neg11d	⊢ ( 𝜑 → 𝐴 = 𝐵 )

Proof

Step	Hyp	Ref	Expression
1		negidd.1	⊢ ( 𝜑 → 𝐴 ∈ ℂ )
2		pncand.2	⊢ ( 𝜑 → 𝐵 ∈ ℂ )
3		neg11d.3	⊢ ( 𝜑 → - 𝐴 = - 𝐵 )
4	1 2	neg11ad	⊢ ( 𝜑 → ( - 𝐴 = - 𝐵 ↔ 𝐴 = 𝐵 ) )
5	3 4	mpbid	⊢ ( 𝜑 → 𝐴 = 𝐵 )