Theorem 8p1e9 8172

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 8105	. 2 ⊢ 9 = (8 + 1)
2	1	eqcomi 2085	1 ⊢ (8 + 1) = 9

Syntax hints:   = wceq 1284  (class class class)co 5532  1c1 6982   + caddc 6984  8c8 8095  9c9 8096

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-5 1376  ax-gen 1378  ax-ext 2063

This theorem depends on definitions:  df-bi 115  df-cleq 2074  df-9 8105

This theorem is referenced by: (None)