Metamath Proof Explorer


Theorem 2timesd

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

Ref Expression
Hypothesis 2timesd.1 φA
Assertion 2timesd φ2A=A+A

Proof

Step Hyp Ref Expression
1 2timesd.1 φA
2 2times A2A=A+A
3 1 2 syl φ2A=A+A