Theorem 8p1e9 8860

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 8786	. 2 ⊢ 9 = (8 + 1)
2	1	eqcomi 2143	1 ⊢ (8 + 1) = 9

Syntax hints:   = wceq 1331  (class class class)co 5774  1c1 7621   + caddc 7623  8c8 8777  9c9 8778

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 1423  ax-gen 1425  ax-ext 2121

This theorem depends on definitions:  df-bi 116  df-cleq 2132  df-9 8786

This theorem is referenced by:  cos2bnd  11467