Metamath Proof Explorer


Theorem xaddid2d

Description: 0 is a left identity for extended real addition. (Contributed by Glauco Siliprandi, 17-Aug-2020)

Ref Expression
Hypothesis xaddid2d.1 φA*
Assertion xaddid2d φ0+𝑒A=A

Proof

Step Hyp Ref Expression
1 xaddid2d.1 φA*
2 xaddid2 A*0+𝑒A=A
3 1 2 syl φ0+𝑒A=A