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Metamath Proof Explorer

Theorem bcxmaslem1

Description: Lemma for bcxmas . (Contributed by Paul Chapman, 18-May-2007)

Ref Expression
Assertion bcxmaslem1 
|- ( A = B -> ( ( N + A ) _C A ) = ( ( N + B ) _C B ) )

Proof

Step Hyp Ref Expression
1 oveq2 
 |-  ( A = B -> ( N + A ) = ( N + B ) )
2 id 
 |-  ( A = B -> A = B )
3 1 2 oveq12d 
 |-  ( A = B -> ( ( N + A ) _C A ) = ( ( N + B ) _C B ) )