Theorem 8p1e9 9447

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 9372	. 2 ⊢ 9 = (8 + 1)
2	1	eqcomi 2242	1 ⊢ (8 + 1) = 9

This proof depends on syntax axioms:   = wceq 1402  (class class class)co 6085  1c1 8180   + caddc 8182  8c8 9363  9c9 9364

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1500  ax-gen 1502  ax-ext 2220

This proof depends on definitions:  df-bi 117  df-cleq 2231  df-9 9372

This theorem is used by:  cos2bnd  12543  19prm  13252  139prm  13258  317prm  13260  1259lem2  13263  1259lem4  13265  1259lem5  13266  1259prm  13267  log2ublog2  16143