Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > MPE Home > Th. List > expnlbnd | Structured version Visualization version GIF version |
Description: The reciprocal of exponentiation with a base greater than 1 has no positive lower bound. (Contributed by NM, 18-Jul-2008.) |
Ref | Expression |
---|---|
expnlbnd | ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / (𝐵↑𝑘)) < 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | rpre 12594 | . . . 4 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ∈ ℝ) | |
2 | rpne0 12602 | . . . 4 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ≠ 0) | |
3 | 1, 2 | rereccld 11659 | . . 3 ⊢ (𝐴 ∈ ℝ+ → (1 / 𝐴) ∈ ℝ) |
4 | expnbnd 13799 | . . 3 ⊢ (((1 / 𝐴) ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘)) | |
5 | 3, 4 | syl3an1 1165 | . 2 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘)) |
6 | rpregt0 12600 | . . . . 5 ⊢ (𝐴 ∈ ℝ+ → (𝐴 ∈ ℝ ∧ 0 < 𝐴)) | |
7 | 6 | 3ad2ant1 1135 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → (𝐴 ∈ ℝ ∧ 0 < 𝐴)) |
8 | nnnn0 12097 | . . . . . . . 8 ⊢ (𝑘 ∈ ℕ → 𝑘 ∈ ℕ0) | |
9 | reexpcl 13652 | . . . . . . . 8 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℕ0) → (𝐵↑𝑘) ∈ ℝ) | |
10 | 8, 9 | sylan2 596 | . . . . . . 7 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℕ) → (𝐵↑𝑘) ∈ ℝ) |
11 | 10 | adantlr 715 | . . . . . 6 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → (𝐵↑𝑘) ∈ ℝ) |
12 | simpll 767 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 𝐵 ∈ ℝ) | |
13 | nnz 12199 | . . . . . . . 8 ⊢ (𝑘 ∈ ℕ → 𝑘 ∈ ℤ) | |
14 | 13 | adantl 485 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 𝑘 ∈ ℤ) |
15 | 0lt1 11354 | . . . . . . . . . 10 ⊢ 0 < 1 | |
16 | 0re 10835 | . . . . . . . . . . 11 ⊢ 0 ∈ ℝ | |
17 | 1re 10833 | . . . . . . . . . . 11 ⊢ 1 ∈ ℝ | |
18 | lttr 10909 | . . . . . . . . . . 11 ⊢ ((0 ∈ ℝ ∧ 1 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 1 ∧ 1 < 𝐵) → 0 < 𝐵)) | |
19 | 16, 17, 18 | mp3an12 1453 | . . . . . . . . . 10 ⊢ (𝐵 ∈ ℝ → ((0 < 1 ∧ 1 < 𝐵) → 0 < 𝐵)) |
20 | 15, 19 | mpani 696 | . . . . . . . . 9 ⊢ (𝐵 ∈ ℝ → (1 < 𝐵 → 0 < 𝐵)) |
21 | 20 | imp 410 | . . . . . . . 8 ⊢ ((𝐵 ∈ ℝ ∧ 1 < 𝐵) → 0 < 𝐵) |
22 | 21 | adantr 484 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 0 < 𝐵) |
23 | expgt0 13668 | . . . . . . 7 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℤ ∧ 0 < 𝐵) → 0 < (𝐵↑𝑘)) | |
24 | 12, 14, 22, 23 | syl3anc 1373 | . . . . . 6 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 0 < (𝐵↑𝑘)) |
25 | 11, 24 | jca 515 | . . . . 5 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) |
26 | 25 | 3adantl1 1168 | . . . 4 ⊢ (((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) |
27 | ltrec1 11719 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 0 < 𝐴) ∧ ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) → ((1 / 𝐴) < (𝐵↑𝑘) ↔ (1 / (𝐵↑𝑘)) < 𝐴)) | |
28 | 7, 26, 27 | syl2an2r 685 | . . 3 ⊢ (((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((1 / 𝐴) < (𝐵↑𝑘) ↔ (1 / (𝐵↑𝑘)) < 𝐴)) |
29 | 28 | rexbidva 3215 | . 2 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → (∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘) ↔ ∃𝑘 ∈ ℕ (1 / (𝐵↑𝑘)) < 𝐴)) |
30 | 5, 29 | mpbid 235 | 1 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / (𝐵↑𝑘)) < 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 209 ∧ wa 399 ∧ w3a 1089 ∈ wcel 2110 ∃wrex 3062 class class class wbr 5053 (class class class)co 7213 ℝcr 10728 0cc0 10729 1c1 10730 < clt 10867 / cdiv 11489 ℕcn 11830 ℕ0cn0 12090 ℤcz 12176 ℝ+crp 12586 ↑cexp 13635 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1803 ax-4 1817 ax-5 1918 ax-6 1976 ax-7 2016 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2158 ax-12 2175 ax-ext 2708 ax-sep 5192 ax-nul 5199 ax-pow 5258 ax-pr 5322 ax-un 7523 ax-cnex 10785 ax-resscn 10786 ax-1cn 10787 ax-icn 10788 ax-addcl 10789 ax-addrcl 10790 ax-mulcl 10791 ax-mulrcl 10792 ax-mulcom 10793 ax-addass 10794 ax-mulass 10795 ax-distr 10796 ax-i2m1 10797 ax-1ne0 10798 ax-1rid 10799 ax-rnegex 10800 ax-rrecex 10801 ax-cnre 10802 ax-pre-lttri 10803 ax-pre-lttrn 10804 ax-pre-ltadd 10805 ax-pre-mulgt0 10806 ax-pre-sup 10807 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 848 df-3or 1090 df-3an 1091 df-tru 1546 df-fal 1556 df-ex 1788 df-nf 1792 df-sb 2071 df-mo 2539 df-eu 2568 df-clab 2715 df-cleq 2729 df-clel 2816 df-nfc 2886 df-ne 2941 df-nel 3047 df-ral 3066 df-rex 3067 df-reu 3068 df-rmo 3069 df-rab 3070 df-v 3410 df-sbc 3695 df-csb 3812 df-dif 3869 df-un 3871 df-in 3873 df-ss 3883 df-pss 3885 df-nul 4238 df-if 4440 df-pw 4515 df-sn 4542 df-pr 4544 df-tp 4546 df-op 4548 df-uni 4820 df-iun 4906 df-br 5054 df-opab 5116 df-mpt 5136 df-tr 5162 df-id 5455 df-eprel 5460 df-po 5468 df-so 5469 df-fr 5509 df-we 5511 df-xp 5557 df-rel 5558 df-cnv 5559 df-co 5560 df-dm 5561 df-rn 5562 df-res 5563 df-ima 5564 df-pred 6160 df-ord 6216 df-on 6217 df-lim 6218 df-suc 6219 df-iota 6338 df-fun 6382 df-fn 6383 df-f 6384 df-f1 6385 df-fo 6386 df-f1o 6387 df-fv 6388 df-riota 7170 df-ov 7216 df-oprab 7217 df-mpo 7218 df-om 7645 df-2nd 7762 df-wrecs 8047 df-recs 8108 df-rdg 8146 df-er 8391 df-en 8627 df-dom 8628 df-sdom 8629 df-sup 9058 df-inf 9059 df-pnf 10869 df-mnf 10870 df-xr 10871 df-ltxr 10872 df-le 10873 df-sub 11064 df-neg 11065 df-div 11490 df-nn 11831 df-n0 12091 df-z 12177 df-uz 12439 df-rp 12587 df-fl 13367 df-seq 13575 df-exp 13636 |
This theorem is referenced by: expnlbnd2 13801 opnmbllem 24498 opnmbllem0 35550 heiborlem7 35712 |
Copyright terms: Public domain | W3C validator |