Metamath Proof Explorer


Theorem mullidd

Description: Identity law for multiplication. (Contributed by Mario Carneiro, 27-May-2016)

Ref Expression
Hypothesis addcld.1 φ A
Assertion mullidd φ 1 A = A

Proof

Step Hyp Ref Expression
1 addcld.1 φ A
2 mullid A 1 A = A
3 1 2 syl φ 1 A = A