Theorem negcld

Description: Closure law for negative. (Contributed by Mario Carneiro, 27-May-2016)

	Ref	Expression
Hypothesis	negidd.1	$$⊢\phi \to A\in ℂ$$
Assertion	negcld	$$⊢\phi \to -A\in ℂ$$

Proof

Step	Hyp	Ref	Expression
1		negidd.1	$$⊢\phi \to A\in ℂ$$
2		negcl	$$⊢A\in ℂ\to -A\in ℂ$$
3	1 2	syl	$$⊢\phi \to -A\in ℂ$$