Theorem uneq2 3377

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 3376	. 2 |- ( A = B -> ( A u. C ) = ( B u. C ) )
2		uncom 3373	. 2 |- ( C u. A ) = ( A u. C )
3		uncom 3373	. 2 |- ( C u. B ) = ( B u. C )
4	1, 2, 3	3eqtr4g 2296	1 |- ( A = B -> ( C u. A ) = ( C u. B ) )

Syntax hints:   -> wi 4   = wceq 1402   u. cun 3218

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 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-ext 2220

This theorem depends on definitions:  df-bi 117  df-tru 1405  df-nf 1514  df-sb 1816  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-v 2823  df-un 3224

This theorem is referenced by:  uneq12  3378  uneq2i  3380  uneq2d  3383  uneqin  3482  disjssun  3588  uniprg  3948  sucprc  4555  unexb  4586  unfiexmid  7218  unfidisj  7222  hashunlem  11225  bdunexb  16863  bj-unexg  16864