Theorem uneqri 3085

Description: Inference from membership to union. (Contributed by NM, 5-Aug-1993.)

Hypothesis

Ref	Expression
uneqri.1	|- ( ( x e. A \/ x e. B ) <-> x e. C )

Assertion

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

Distinct variable groups:   x, A   x, B   x, C

Proof of Theorem uneqri

Step	Hyp	Ref	Expression
1		elun 3084	. . 3 |- ( x e. ( A u. B ) <-> ( x e. A \/ x e. B ) )
2		uneqri.1	. . 3 |- ( ( x e. A \/ x e. B ) <-> x e. C )
3	1, 2	bitri 173	. 2 |- ( x e. ( A u. B ) <-> x e. C )
4	3	eqriv 2037	1 |- ( A u. B ) = C

Syntax hints:   <-> wb 98   \/ wo 629   = wceq 1243   e. wcel 1393   u. cun 2915

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022

This theorem depends on definitions:  df-bi 110  df-tru 1246  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-v 2559  df-un 2922

This theorem is referenced by:  unidm  3086  uncom  3087  unass  3100  undi  3185  unab  3204  un0  3251