Metamath Proof Explorer


Theorem 1p1times

Description: Two times a number. (Contributed by NM, 18-May-1999) (Revised by Mario Carneiro, 27-May-2016)

Ref Expression
Assertion 1p1times A 1 + 1 A = A + A

Proof

Step Hyp Ref Expression
1 1cnd A 1
2 id A A
3 mulid2 A 1 A = A
4 3 3 oveq12d A 1 A + 1 A = A + A
5 1 2 1 4 joinlmuladdmuld A 1 + 1 A = A + A