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Theorem expnlbnd 11977
Description: The reciprocal of exponentiation with a mantissa greater than 1 has no lower bound. (Contributed by NM, 18-Jul-2008.)
Assertion
Ref Expression
expnlbnd  |-  ( ( A  e.  RR+  /\  B  e.  RR  /\  1  < 
B )  ->  E. k  e.  NN  ( 1  / 
( B ^ k
) )  <  A
)
Distinct variable groups:    A, k    B, k

Proof of Theorem expnlbnd
StepHypRef Expression
1 rpre 10984 . . . 4  |-  ( A  e.  RR+  ->  A  e.  RR )
2 rpne0 10993 . . . 4  |-  ( A  e.  RR+  ->  A  =/=  0 )
31, 2rereccld 10145 . . 3  |-  ( A  e.  RR+  ->  ( 1  /  A )  e.  RR )
4 expnbnd 11976 . . 3  |-  ( ( ( 1  /  A
)  e.  RR  /\  B  e.  RR  /\  1  <  B )  ->  E. k  e.  NN  ( 1  /  A )  <  ( B ^ k ) )
53, 4syl3an1 1244 . 2  |-  ( ( A  e.  RR+  /\  B  e.  RR  /\  1  < 
B )  ->  E. k  e.  NN  ( 1  /  A )  <  ( B ^ k ) )
6 rpregt0 10991 . . . . . 6  |-  ( A  e.  RR+  ->  ( A  e.  RR  /\  0  <  A ) )
763ad2ant1 1002 . . . . 5  |-  ( ( A  e.  RR+  /\  B  e.  RR  /\  1  < 
B )  ->  ( A  e.  RR  /\  0  <  A ) )
87adantr 462 . . . 4  |-  ( ( ( A  e.  RR+  /\  B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  ( A  e.  RR  /\  0  <  A ) )
9 nnnn0 10573 . . . . . . . 8  |-  ( k  e.  NN  ->  k  e.  NN0 )
10 reexpcl 11865 . . . . . . . 8  |-  ( ( B  e.  RR  /\  k  e.  NN0 )  -> 
( B ^ k
)  e.  RR )
119, 10sylan2 471 . . . . . . 7  |-  ( ( B  e.  RR  /\  k  e.  NN )  ->  ( B ^ k
)  e.  RR )
1211adantlr 707 . . . . . 6  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  ( B ^
k )  e.  RR )
13 simpll 746 . . . . . . 7  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  B  e.  RR )
14 nnz 10655 . . . . . . . 8  |-  ( k  e.  NN  ->  k  e.  ZZ )
1514adantl 463 . . . . . . 7  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  k  e.  ZZ )
16 0lt1 9849 . . . . . . . . . 10  |-  0  <  1
17 0re 9373 . . . . . . . . . . 11  |-  0  e.  RR
18 1re 9372 . . . . . . . . . . 11  |-  1  e.  RR
19 lttr 9438 . . . . . . . . . . 11  |-  ( ( 0  e.  RR  /\  1  e.  RR  /\  B  e.  RR )  ->  (
( 0  <  1  /\  1  <  B )  ->  0  <  B
) )
2017, 18, 19mp3an12 1297 . . . . . . . . . 10  |-  ( B  e.  RR  ->  (
( 0  <  1  /\  1  <  B )  ->  0  <  B
) )
2116, 20mpani 669 . . . . . . . . 9  |-  ( B  e.  RR  ->  (
1  <  B  ->  0  <  B ) )
2221imp 429 . . . . . . . 8  |-  ( ( B  e.  RR  /\  1  <  B )  -> 
0  <  B )
2322adantr 462 . . . . . . 7  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  0  <  B
)
24 expgt0 11880 . . . . . . 7  |-  ( ( B  e.  RR  /\  k  e.  ZZ  /\  0  <  B )  ->  0  <  ( B ^ k
) )
2513, 15, 23, 24syl3anc 1211 . . . . . 6  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  0  <  ( B ^ k ) )
2612, 25jca 529 . . . . 5  |-  ( ( ( B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  ( ( B ^ k )  e.  RR  /\  0  < 
( B ^ k
) ) )
27263adantl1 1137 . . . 4  |-  ( ( ( A  e.  RR+  /\  B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  ( ( B ^
k )  e.  RR  /\  0  <  ( B ^ k ) ) )
28 ltrec1 10206 . . . 4  |-  ( ( ( A  e.  RR  /\  0  <  A )  /\  ( ( B ^ k )  e.  RR  /\  0  < 
( B ^ k
) ) )  -> 
( ( 1  /  A )  <  ( B ^ k )  <->  ( 1  /  ( B ^
k ) )  < 
A ) )
298, 27, 28syl2anc 654 . . 3  |-  ( ( ( A  e.  RR+  /\  B  e.  RR  /\  1  <  B )  /\  k  e.  NN )  ->  ( ( 1  /  A )  <  ( B ^ k )  <->  ( 1  /  ( B ^
k ) )  < 
A ) )
3029rexbidva 2722 . 2  |-  ( ( A  e.  RR+  /\  B  e.  RR  /\  1  < 
B )  ->  ( E. k  e.  NN  ( 1  /  A
)  <  ( B ^ k )  <->  E. k  e.  NN  ( 1  / 
( B ^ k
) )  <  A
) )
315, 30mpbid 210 1  |-  ( ( A  e.  RR+  /\  B  e.  RR  /\  1  < 
B )  ->  E. k  e.  NN  ( 1  / 
( B ^ k
) )  <  A
)
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 184    /\ wa 369    /\ w3a 958    e. wcel 1755   E.wrex 2706   class class class wbr 4280  (class class class)co 6080   RRcr 9268   0cc0 9269   1c1 9270    < clt 9405    / cdiv 9980   NNcn 10309   NN0cn0 10566   ZZcz 10633   RR+crp 10978   ^cexp 11848
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1594  ax-4 1605  ax-5 1669  ax-6 1707  ax-7 1727  ax-8 1757  ax-9 1759  ax-10 1774  ax-11 1779  ax-12 1791  ax-13 1942  ax-ext 2414  ax-sep 4401  ax-nul 4409  ax-pow 4458  ax-pr 4519  ax-un 6361  ax-cnex 9325  ax-resscn 9326  ax-1cn 9327  ax-icn 9328  ax-addcl 9329  ax-addrcl 9330  ax-mulcl 9331  ax-mulrcl 9332  ax-mulcom 9333  ax-addass 9334  ax-mulass 9335  ax-distr 9336  ax-i2m1 9337  ax-1ne0 9338  ax-1rid 9339  ax-rnegex 9340  ax-rrecex 9341  ax-cnre 9342  ax-pre-lttri 9343  ax-pre-lttrn 9344  ax-pre-ltadd 9345  ax-pre-mulgt0 9346  ax-pre-sup 9347
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-3or 959  df-3an 960  df-tru 1365  df-ex 1590  df-nf 1593  df-sb 1700  df-eu 2258  df-mo 2259  df-clab 2420  df-cleq 2426  df-clel 2429  df-nfc 2558  df-ne 2598  df-nel 2599  df-ral 2710  df-rex 2711  df-reu 2712  df-rmo 2713  df-rab 2714  df-v 2964  df-sbc 3176  df-csb 3277  df-dif 3319  df-un 3321  df-in 3323  df-ss 3330  df-pss 3332  df-nul 3626  df-if 3780  df-pw 3850  df-sn 3866  df-pr 3868  df-tp 3870  df-op 3872  df-uni 4080  df-iun 4161  df-br 4281  df-opab 4339  df-mpt 4340  df-tr 4374  df-eprel 4619  df-id 4623  df-po 4628  df-so 4629  df-fr 4666  df-we 4668  df-ord 4709  df-on 4710  df-lim 4711  df-suc 4712  df-xp 4833  df-rel 4834  df-cnv 4835  df-co 4836  df-dm 4837  df-rn 4838  df-res 4839  df-ima 4840  df-iota 5369  df-fun 5408  df-fn 5409  df-f 5410  df-f1 5411  df-fo 5412  df-f1o 5413  df-fv 5414  df-riota 6039  df-ov 6083  df-oprab 6084  df-mpt2 6085  df-om 6466  df-2nd 6567  df-recs 6818  df-rdg 6852  df-er 7089  df-en 7299  df-dom 7300  df-sdom 7301  df-sup 7679  df-pnf 9407  df-mnf 9408  df-xr 9409  df-ltxr 9410  df-le 9411  df-sub 9584  df-neg 9585  df-div 9981  df-nn 10310  df-n0 10567  df-z 10634  df-uz 10849  df-rp 10979  df-fl 11625  df-seq 11790  df-exp 11849
This theorem is referenced by:  expnlbnd2  11978  opnmbllem  20922  opnmbllem0  28268  heiborlem7  28557
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