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Metamath Proof Explorer

Theorem preq1i

Description: Equality inference for unordered pairs. (Contributed by NM, 19-Oct-2012)

Ref Expression
Hypothesis preq1i.1 ⊢ A = B
Assertion preq1i ⊢ A C = B C

Proof

Step Hyp Ref Expression
1 preq1i.1 ⊢ A = B
2 preq1 ⊢ A = B → A C = B C
3 1 2 ax-mp ⊢ A C = B C