Theorem 8p1e9 9212

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 9137	. 2 ⊢ 9 = (8 + 1)
2	1	eqcomi 2211	1 ⊢ (8 + 1) = 9

Syntax hints:   = wceq 1373  (class class class)co 5967  1c1 7961   + caddc 7963  8c8 9128  9c9 9129

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 1471  ax-gen 1473  ax-ext 2189

This theorem depends on definitions:  df-bi 117  df-cleq 2200  df-9 9137

This theorem is referenced by:  cos2bnd  12186