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Theorem ltmul1 8619
Description: Multiplication of both sides of 'less than' by a positive number. Theorem I.19 of [Apostol] p. 20. Part of Definition 11.2.7(vi) of [HoTT], p. (varies). (Contributed by NM, 13-Feb-2005.) (Revised by Mario Carneiro, 27-May-2016.)
Assertion
Ref Expression
ltmul1  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  -> 
( A  <  B  <->  ( A  x.  C )  <  ( B  x.  C ) ) )

Proof of Theorem ltmul1
Dummy variable  x is distinct from all other variables.
StepHypRef Expression
1 ltmul1a 8618 . . 3  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  A  < 
B )  ->  ( A  x.  C )  <  ( B  x.  C
) )
21ex 115 . 2  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  -> 
( A  <  B  ->  ( A  x.  C
)  <  ( B  x.  C ) ) )
3 recexgt0 8607 . . . 4  |-  ( ( C  e.  RR  /\  0  <  C )  ->  E. x  e.  RR  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) )
433ad2ant3 1022 . . 3  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  ->  E. x  e.  RR  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) )
5 simpl1 1002 . . . . . . . . . 10  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  A  e.  RR )
6 simpl3l 1054 . . . . . . . . . 10  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  C  e.  RR )
75, 6remulcld 8057 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  ( A  x.  C )  e.  RR )
8 simpl2 1003 . . . . . . . . . 10  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  B  e.  RR )
98, 6remulcld 8057 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  ( B  x.  C )  e.  RR )
10 simprl 529 . . . . . . . . . 10  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  x  e.  RR )
11 simprrl 539 . . . . . . . . . 10  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  0  <  x )
1210, 11jca 306 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  (
x  e.  RR  /\  0  <  x ) )
137, 9, 123jca 1179 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  (
( A  x.  C
)  e.  RR  /\  ( B  x.  C
)  e.  RR  /\  ( x  e.  RR  /\  0  <  x ) ) )
14 ltmul1a 8618 . . . . . . . 8  |-  ( ( ( ( A  x.  C )  e.  RR  /\  ( B  x.  C
)  e.  RR  /\  ( x  e.  RR  /\  0  <  x ) )  /\  ( A  x.  C )  < 
( B  x.  C
) )  ->  (
( A  x.  C
)  x.  x )  <  ( ( B  x.  C )  x.  x ) )
1513, 14sylan 283 . . . . . . 7  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  (
( A  x.  C
)  x.  x )  <  ( ( B  x.  C )  x.  x ) )
165recnd 8055 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  A  e.  CC )
1716adantr 276 . . . . . . . 8  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  A  e.  CC )
186recnd 8055 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  C  e.  CC )
1918adantr 276 . . . . . . . 8  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  C  e.  CC )
2010recnd 8055 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  x  e.  CC )
2120adantr 276 . . . . . . . 8  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  x  e.  CC )
2217, 19, 21mulassd 8050 . . . . . . 7  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  (
( A  x.  C
)  x.  x )  =  ( A  x.  ( C  x.  x
) ) )
238recnd 8055 . . . . . . . . 9  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  B  e.  CC )
2423adantr 276 . . . . . . . 8  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  B  e.  CC )
2524, 19, 21mulassd 8050 . . . . . . 7  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  (
( B  x.  C
)  x.  x )  =  ( B  x.  ( C  x.  x
) ) )
2615, 22, 253brtr3d 4064 . . . . . 6  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( A  x.  ( C  x.  x ) )  < 
( B  x.  ( C  x.  x )
) )
27 simprrr 540 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  ( C  x.  x )  =  1 )
2827adantr 276 . . . . . . 7  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( C  x.  x )  =  1 )
2928oveq2d 5938 . . . . . 6  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( A  x.  ( C  x.  x ) )  =  ( A  x.  1 ) )
3028oveq2d 5938 . . . . . 6  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( B  x.  ( C  x.  x ) )  =  ( B  x.  1 ) )
3126, 29, 303brtr3d 4064 . . . . 5  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( A  x.  1 )  <  ( B  x.  1 ) )
3217mulridd 8043 . . . . 5  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( A  x.  1 )  =  A )
3324mulridd 8043 . . . . 5  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  ( B  x.  1 )  =  B )
3431, 32, 333brtr3d 4064 . . . 4  |-  ( ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  ( 0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  /\  ( A  x.  C )  <  ( B  x.  C
) )  ->  A  <  B )
3534ex 115 . . 3  |-  ( ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  /\  ( x  e.  RR  /\  (
0  <  x  /\  ( C  x.  x
)  =  1 ) ) )  ->  (
( A  x.  C
)  <  ( B  x.  C )  ->  A  <  B ) )
364, 35rexlimddv 2619 . 2  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  -> 
( ( A  x.  C )  <  ( B  x.  C )  ->  A  <  B ) )
372, 36impbid 129 1  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  ( C  e.  RR  /\  0  <  C ) )  -> 
( A  <  B  <->  ( A  x.  C )  <  ( B  x.  C ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 104    <-> wb 105    /\ w3a 980    = wceq 1364    e. wcel 2167   E.wrex 2476   class class class wbr 4033  (class class class)co 5922   CCcc 7877   RRcr 7878   0cc0 7879   1c1 7880    x. cmul 7884    < clt 8061
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-in1 615  ax-in2 616  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-13 2169  ax-14 2170  ax-ext 2178  ax-sep 4151  ax-pow 4207  ax-pr 4242  ax-un 4468  ax-setind 4573  ax-cnex 7970  ax-resscn 7971  ax-1cn 7972  ax-1re 7973  ax-icn 7974  ax-addcl 7975  ax-addrcl 7976  ax-mulcl 7977  ax-mulrcl 7978  ax-addcom 7979  ax-mulcom 7980  ax-addass 7981  ax-mulass 7982  ax-distr 7983  ax-i2m1 7984  ax-1rid 7986  ax-0id 7987  ax-rnegex 7988  ax-precex 7989  ax-cnre 7990  ax-pre-ltadd 7995  ax-pre-mulgt0 7996
This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-fal 1370  df-nf 1475  df-sb 1777  df-eu 2048  df-mo 2049  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-ne 2368  df-nel 2463  df-ral 2480  df-rex 2481  df-reu 2482  df-rab 2484  df-v 2765  df-sbc 2990  df-dif 3159  df-un 3161  df-in 3163  df-ss 3170  df-pw 3607  df-sn 3628  df-pr 3629  df-op 3631  df-uni 3840  df-br 4034  df-opab 4095  df-id 4328  df-xp 4669  df-rel 4670  df-cnv 4671  df-co 4672  df-dm 4673  df-iota 5219  df-fun 5260  df-fv 5266  df-riota 5877  df-ov 5925  df-oprab 5926  df-mpo 5927  df-pnf 8063  df-mnf 8064  df-ltxr 8066  df-sub 8199  df-neg 8200
This theorem is referenced by:  lemul1  8620  reapmul1lem  8621  ltmul2  8883  ltdiv1  8895  ltdiv23  8919  recp1lt1  8926  ltmul1i  8947  ltmul1d  9813  mertenslemi1  11700  flodddiv4t2lthalf  12104  qnumgt0  12366  4sqlem12  12571  tangtx  15074  lgsquadlem1  15318  lgsquadlem2  15319
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