Theorem uneq2 3357

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 3356	. 2 |- ( A = B -> ( A u. C ) = ( B u. C ) )
2		uncom 3353	. 2 |- ( C u. A ) = ( A u. C )
3		uncom 3353	. 2 |- ( C u. B ) = ( B u. C )
4	1, 2, 3	3eqtr4g 2289	1 |- ( A = B -> ( C u. A ) = ( C u. B ) )

Syntax hints:   -> wi 4   = wceq 1398   u. cun 3199

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 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-tru 1401  df-nf 1510  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2364  df-v 2805  df-un 3205

This theorem is referenced by:  uneq12  3358  uneq2i  3360  uneq2d  3363  uneqin  3460  disjssun  3560  uniprg  3913  sucprc  4515  unexb  4545  unfiexmid  7153  unfidisj  7157  hashunlem  11130  bdunexb  16636  bj-unexg  16637