Theorem 8p1e9 9131

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 9056	. 2 ⊢ 9 = (8 + 1)
2	1	eqcomi 2200	1 ⊢ (8 + 1) = 9

Syntax hints:   = wceq 1364  (class class class)co 5922  1c1 7880   + caddc 7882  8c8 9047  9c9 9048

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 1461  ax-gen 1463  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-cleq 2189  df-9 9056

This theorem is referenced by:  cos2bnd  11925