This is an inofficial mirror of http://metamath.tirix.org for personal testing of a visualizer extension only.

Metamath Proof Explorer

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