Theorem divnegd

Description: Move negative sign inside of a division. (Contributed by Mario Carneiro, 27-May-2016)

	Ref	Expression
Hypotheses	div1d.1	$$⊢\phi \to A\in ℂ$$
	divcld.2	$$⊢\phi \to B\in ℂ$$
	divcld.3	$$⊢\phi \to B\ne 0$$
Assertion	divnegd	$$⊢\phi \to -\frac{A}{B}=\frac{-A}{B}$$

Proof

Step	Hyp	Ref	Expression
1		div1d.1	$$⊢\phi \to A\in ℂ$$
2		divcld.2	$$⊢\phi \to B\in ℂ$$
3		divcld.3	$$⊢\phi \to B\ne 0$$
4		divneg	$$⊢\left(A\in ℂ\wedge B\in ℂ\wedge B\ne 0\right)\to -\frac{A}{B}=\frac{-A}{B}$$
5	1 2 3 4	syl3anc	$$⊢\phi \to -\frac{A}{B}=\frac{-A}{B}$$