Theorem 8p1e9 8997

Description: 8 + 1 = 9. (Contributed by Mario Carneiro, 18-Apr-2015.)

Assertion

Ref	Expression
8p1e9	|- ( 8 + 1 ) = 9

Proof of Theorem 8p1e9

Step	Hyp	Ref	Expression
1		df-9 8923	. 2 |- 9 = ( 8 + 1 )
2	1	eqcomi 2169	1 |- ( 8 + 1 ) = 9

Syntax hints:   = wceq 1343  (class class class)co 5842   1c1 7754   + caddc 7756   8c8 8914   9c9 8915

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1435  ax-gen 1437  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-cleq 2158  df-9 8923

This theorem is referenced by:  cos2bnd  11701