Theorem negneg1e1

Description: -u -u 1 is 1. (Contributed by David A. Wheeler, 8-Dec-2018)

	Ref	Expression
Assertion	negneg1e1	⊢ - - 1 = 1

Proof

Step	Hyp	Ref	Expression
1		ax-1cn	⊢ 1 ∈ ℂ
2	1	negnegi	⊢ - - 1 = 1