Theorem xnegeq 9763

Description: Equality of two extended numbers with -e in front of them. (Contributed by FL, 26-Dec-2011.) (Proof shortened by Mario Carneiro, 20-Aug-2015.)

Assertion

Ref	Expression
xnegeq	|- ( A = B -> -e A = -e B )

Proof of Theorem xnegeq

Step	Hyp	Ref	Expression
1		eqeq1 2172	. . 3 |- ( A = B -> ( A = +oo <-> B = +oo ) )
2		eqeq1 2172	. . . 4 |- ( A = B -> ( A = -oo <-> B = -oo ) )
3		negeq 8091	. . . 4 |- ( A = B -> -u A = -u B )
4	2, 3	ifbieq2d 3544	. . 3 |- ( A = B -> if ( A = -oo , +oo , -u A ) = if ( B = -oo , +oo , -u B ) )
5	1, 4	ifbieq2d 3544	. 2 |- ( A = B -> if ( A = +oo , -oo , if ( A = -oo , +oo , -u A ) ) = if ( B = +oo , -oo , if ( B = -oo , +oo , -u B ) ) )
6		df-xneg 9708	. 2 |- -e A = if ( A = +oo , -oo , if ( A = -oo , +oo , -u A ) )
7		df-xneg 9708	. 2 |- -e B = if ( B = +oo , -oo , if ( B = -oo , +oo , -u B ) )
8	5, 6, 7	3eqtr4g 2224	1 |- ( A = B -> -e A = -e B )

Syntax hints:   -> wi 4   = wceq 1343   ifcif 3520   +oocpnf 7930   -oocmnf 7931   -ucneg 8070   -ecxne 9705

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-3an 970  df-tru 1346  df-nf 1449  df-sb 1751  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-rex 2450  df-rab 2453  df-v 2728  df-un 3120  df-if 3521  df-sn 3582  df-pr 3583  df-op 3585  df-uni 3790  df-br 3983  df-iota 5153  df-fv 5196  df-ov 5845  df-neg 8072  df-xneg 9708

This theorem is referenced by:  xnegcl  9768  xnegneg  9769  xneg11  9770  xltnegi  9771  xnegid  9795  xnegdi  9804  xsubge0  9817  xposdif  9818  xlesubadd  9819  xrnegiso  11203  infxrnegsupex  11204  xrminmax  11206  xrminrecl  11214  xrminadd  11216  xblss2ps  13044  xblss2  13045