Theorem 8p1e9 9122

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 9048	. 2 |- 9 = ( 8 + 1 )
2	1	eqcomi 2197	1 |- ( 8 + 1 ) = 9

Syntax hints:   = wceq 1364  (class class class)co 5918   1c1 7873   + caddc 7875   8c8 9039   9c9 9040

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1458  ax-gen 1460  ax-ext 2175

This theorem depends on definitions:  df-bi 117  df-cleq 2186  df-9 9048

This theorem is referenced by:  cos2bnd  11903