Theorem rexnegd

Description: Minus a real number. (Contributed by Glauco Siliprandi, 2-Jan-2022)

	Ref	Expression
Hypothesis	rexnegd.1	⊢ ( 𝜑 → 𝐴 ∈ ℝ )
Assertion	rexnegd	⊢ ( 𝜑 → -𝑒 𝐴 = - 𝐴 )

Proof

Step	Hyp	Ref	Expression
1		rexnegd.1	⊢ ( 𝜑 → 𝐴 ∈ ℝ )
2		rexneg	⊢ ( 𝐴 ∈ ℝ → -𝑒 𝐴 = - 𝐴 )
3	1 2	syl	⊢ ( 𝜑 → -𝑒 𝐴 = - 𝐴 )