Theorem 2m1e1

Description: 2 - 1 = 1. The result is on the right-hand-side to be consistent with similar proofs like 4p4e8 . (Contributed by David A. Wheeler, 4-Jan-2017)

	Ref	Expression
Assertion	2m1e1	⊢ ( 2 − 1 ) = 1

Proof

Step	Hyp	Ref	Expression
1		2cn	⊢ 2 ∈ ℂ
2		ax-1cn	⊢ 1 ∈ ℂ
3		1p1e2	⊢ ( 1 + 1 ) = 2
4	1 2 2 3	subaddrii	⊢ ( 2 − 1 ) = 1