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Theorem rexmul 12101
Description: The extended real multiplication when both arguments are real. (Contributed by Mario Carneiro, 20-Aug-2015.)
Assertion
Ref Expression
rexmul  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A xe B )  =  ( A  x.  B ) )

Proof of Theorem rexmul
StepHypRef Expression
1 renepnf 10087 . . . . . . . . . . 11  |-  ( A  e.  RR  ->  A  =/= +oo )
21adantr 481 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  A  =/= +oo )
32necon2bi 2824 . . . . . . . . 9  |-  ( A  = +oo  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
43adantl 482 . . . . . . . 8  |-  ( ( 0  <  B  /\  A  = +oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
5 renemnf 10088 . . . . . . . . . . 11  |-  ( A  e.  RR  ->  A  =/= -oo )
65adantr 481 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  A  =/= -oo )
76necon2bi 2824 . . . . . . . . 9  |-  ( A  = -oo  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
87adantl 482 . . . . . . . 8  |-  ( ( B  <  0  /\  A  = -oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
94, 8jaoi 394 . . . . . . 7  |-  ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
10 renepnf 10087 . . . . . . . . . . 11  |-  ( B  e.  RR  ->  B  =/= +oo )
1110adantl 482 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  B  =/= +oo )
1211necon2bi 2824 . . . . . . . . 9  |-  ( B  = +oo  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
1312adantl 482 . . . . . . . 8  |-  ( ( 0  <  A  /\  B  = +oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
14 renemnf 10088 . . . . . . . . . . 11  |-  ( B  e.  RR  ->  B  =/= -oo )
1514adantl 482 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  B  =/= -oo )
1615necon2bi 2824 . . . . . . . . 9  |-  ( B  = -oo  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
1716adantl 482 . . . . . . . 8  |-  ( ( A  <  0  /\  B  = -oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
1813, 17jaoi 394 . . . . . . 7  |-  ( ( ( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
199, 18jaoi 394 . . . . . 6  |-  ( ( ( ( 0  < 
B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2019con2i 134 . . . . 5  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  -.  ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  (
( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) )
2120iffalsed 4097 . . . 4  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) )  =  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) )
227adantl 482 . . . . . . . 8  |-  ( ( 0  <  B  /\  A  = -oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
233adantl 482 . . . . . . . 8  |-  ( ( B  <  0  /\  A  = +oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2422, 23jaoi 394 . . . . . . 7  |-  ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2516adantl 482 . . . . . . . 8  |-  ( ( 0  <  A  /\  B  = -oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2612adantl 482 . . . . . . . 8  |-  ( ( A  <  0  /\  B  = +oo )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2725, 26jaoi 394 . . . . . . 7  |-  ( ( ( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2824, 27jaoi 394 . . . . . 6  |-  ( ( ( ( 0  < 
B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  ( ( 0  < 
A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) )  ->  -.  ( A  e.  RR  /\  B  e.  RR ) )
2928con2i 134 . . . . 5  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  -.  ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) )
3029iffalsed 4097 . . . 4  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  ( ( 0  < 
A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) )  =  ( A  x.  B ) )
3121, 30eqtrd 2656 . . 3  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) )  =  ( A  x.  B ) )
3231ifeq2d 4105 . 2  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  ( A  x.  B ) ) )
33 rexr 10085 . . 3  |-  ( A  e.  RR  ->  A  e.  RR* )
34 rexr 10085 . . 3  |-  ( B  e.  RR  ->  B  e.  RR* )
35 xmulval 12056 . . 3  |-  ( ( A  e.  RR*  /\  B  e.  RR* )  ->  ( A xe B )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  (
( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) ) )
3633, 34, 35syl2an 494 . 2  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A xe B )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  < 
B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) ) )
37 ifid 4125 . . 3  |-  if ( ( A  =  0  \/  B  =  0 ) ,  ( A  x.  B ) ,  ( A  x.  B
) )  =  ( A  x.  B )
38 oveq1 6657 . . . . . 6  |-  ( A  =  0  ->  ( A  x.  B )  =  ( 0  x.  B ) )
39 mul02lem2 10213 . . . . . . 7  |-  ( B  e.  RR  ->  (
0  x.  B )  =  0 )
4039adantl 482 . . . . . 6  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( 0  x.  B
)  =  0 )
4138, 40sylan9eqr 2678 . . . . 5  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  A  =  0 )  ->  ( A  x.  B )  =  0 )
42 oveq2 6658 . . . . . 6  |-  ( B  =  0  ->  ( A  x.  B )  =  ( A  x.  0 ) )
43 recn 10026 . . . . . . . 8  |-  ( A  e.  RR  ->  A  e.  CC )
4443mul01d 10235 . . . . . . 7  |-  ( A  e.  RR  ->  ( A  x.  0 )  =  0 )
4544adantr 481 . . . . . 6  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A  x.  0 )  =  0 )
4642, 45sylan9eqr 2678 . . . . 5  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  B  =  0 )  ->  ( A  x.  B )  =  0 )
4741, 46jaodan 826 . . . 4  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  ( A  =  0  \/  B  =  0 ) )  -> 
( A  x.  B
)  =  0 )
4847ifeq1da 4116 . . 3  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  if ( ( A  =  0  \/  B  =  0 ) ,  ( A  x.  B
) ,  ( A  x.  B ) )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  ( A  x.  B ) ) )
4937, 48syl5eqr 2670 . 2  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A  x.  B
)  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  ( A  x.  B
) ) )
5032, 36, 493eqtr4d 2666 1  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A xe B )  =  ( A  x.  B ) )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    \/ wo 383    /\ wa 384    = wceq 1483    e. wcel 1990    =/= wne 2794   ifcif 4086   class class class wbr 4653  (class class class)co 6650   RRcr 9935   0cc0 9936    x. cmul 9941   +oocpnf 10071   -oocmnf 10072   RR*cxr 10073    < clt 10074   xecxmu 11945
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949  ax-cnex 9992  ax-resscn 9993  ax-1cn 9994  ax-icn 9995  ax-addcl 9996  ax-addrcl 9997  ax-mulcl 9998  ax-mulrcl 9999  ax-mulcom 10000  ax-addass 10001  ax-mulass 10002  ax-distr 10003  ax-i2m1 10004  ax-1ne0 10005  ax-1rid 10006  ax-rnegex 10007  ax-rrecex 10008  ax-cnre 10009  ax-pre-lttri 10010  ax-pre-lttrn 10011  ax-pre-ltadd 10012
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3or 1038  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ne 2795  df-nel 2898  df-ral 2917  df-rex 2918  df-rab 2921  df-v 3202  df-sbc 3436  df-csb 3534  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-nul 3916  df-if 4087  df-pw 4160  df-sn 4178  df-pr 4180  df-op 4184  df-uni 4437  df-br 4654  df-opab 4713  df-mpt 4730  df-id 5024  df-po 5035  df-so 5036  df-xp 5120  df-rel 5121  df-cnv 5122  df-co 5123  df-dm 5124  df-rn 5125  df-res 5126  df-ima 5127  df-iota 5851  df-fun 5890  df-fn 5891  df-f 5892  df-f1 5893  df-fo 5894  df-f1o 5895  df-fv 5896  df-ov 6653  df-oprab 6654  df-mpt2 6655  df-er 7742  df-en 7956  df-dom 7957  df-sdom 7958  df-pnf 10076  df-mnf 10077  df-xr 10078  df-ltxr 10079  df-xmul 11948
This theorem is referenced by:  xmulid1  12109  xmulgt0  12113  xmulasslem3  12116  xlemul1a  12118  xlemul1  12120  xadddilem  12124  nmoix  22533  nmoi2  22534  metnrmlem3  22664  nmoleub2lem  22914  xrecex  29628  rexdiv  29634  pnfinf  29737  xrge0slmod  29844  esumcst  30125  omssubadd  30362
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