Theorem uneq2 3321

Description: Equality theorem for the union of two classes. (Contributed by NM, 5-Aug-1993.)

Assertion

Ref	Expression
uneq2	|- ( A = B -> ( C u. A ) = ( C u. B ) )

Proof of Theorem uneq2

Step	Hyp	Ref	Expression
1		uneq1 3320	. 2 |- ( A = B -> ( A u. C ) = ( B u. C ) )
2		uncom 3317	. 2 |- ( C u. A ) = ( A u. C )
3		uncom 3317	. 2 |- ( C u. B ) = ( B u. C )
4	1, 2, 3	3eqtr4g 2263	1 |- ( A = B -> ( C u. A ) = ( C u. B ) )

Syntax hints:   -> wi 4   = wceq 1373   u. cun 3164

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-io 711  ax-5 1470  ax-7 1471  ax-gen 1472  ax-ie1 1516  ax-ie2 1517  ax-8 1527  ax-10 1528  ax-11 1529  ax-i12 1530  ax-bndl 1532  ax-4 1533  ax-17 1549  ax-i9 1553  ax-ial 1557  ax-i5r 1558  ax-ext 2187

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-nf 1484  df-sb 1786  df-clab 2192  df-cleq 2198  df-clel 2201  df-nfc 2337  df-v 2774  df-un 3170

This theorem is referenced by:  uneq12  3322  uneq2i  3324  uneq2d  3327  uneqin  3424  disjssun  3524  uniprg  3865  sucprc  4460  unexb  4490  unfiexmid  7017  unfidisj  7021  hashunlem  10951  bdunexb  15893  bj-unexg  15894