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Metamath Proof Explorer

Theorem neg1mulneg1e1

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

		Ref	Expression
	Assertion	neg1mulneg1e1	$⊢ -1 -1 = 1$

Step	Hyp	Ref	Expression
1		ax-1cn	$⊢ 1 \in ℂ$
2	1 1	mul2negi	$⊢ -1 -1 = 1 \cdot 1$
3		1t1e1	$⊢ 1 \cdot 1 = 1$
4	2 3	eqtri	$⊢ -1 -1 = 1$