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Mirrors > Home > MPE Home > Th. List > expnlbnd | Structured version Visualization version GIF version |
Description: The reciprocal of exponentiation with a mantissa greater than 1 has no 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 12251 | . . . 4 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ∈ ℝ) | |
2 | rpne0 12259 | . . . 4 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ≠ 0) | |
3 | 1, 2 | rereccld 11321 | . . 3 ⊢ (𝐴 ∈ ℝ+ → (1 / 𝐴) ∈ ℝ) |
4 | expnbnd 13447 | . . 3 ⊢ (((1 / 𝐴) ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘)) | |
5 | 3, 4 | syl3an1 1156 | . 2 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘)) |
6 | rpregt0 12257 | . . . . 5 ⊢ (𝐴 ∈ ℝ+ → (𝐴 ∈ ℝ ∧ 0 < 𝐴)) | |
7 | 6 | 3ad2ant1 1126 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → (𝐴 ∈ ℝ ∧ 0 < 𝐴)) |
8 | nnnn0 11758 | . . . . . . . 8 ⊢ (𝑘 ∈ ℕ → 𝑘 ∈ ℕ0) | |
9 | reexpcl 13300 | . . . . . . . 8 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℕ0) → (𝐵↑𝑘) ∈ ℝ) | |
10 | 8, 9 | sylan2 592 | . . . . . . 7 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℕ) → (𝐵↑𝑘) ∈ ℝ) |
11 | 10 | adantlr 711 | . . . . . 6 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → (𝐵↑𝑘) ∈ ℝ) |
12 | simpll 763 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 𝐵 ∈ ℝ) | |
13 | nnz 11858 | . . . . . . . 8 ⊢ (𝑘 ∈ ℕ → 𝑘 ∈ ℤ) | |
14 | 13 | adantl 482 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 𝑘 ∈ ℤ) |
15 | 0lt1 11016 | . . . . . . . . . 10 ⊢ 0 < 1 | |
16 | 0re 10496 | . . . . . . . . . . 11 ⊢ 0 ∈ ℝ | |
17 | 1re 10494 | . . . . . . . . . . 11 ⊢ 1 ∈ ℝ | |
18 | lttr 10570 | . . . . . . . . . . 11 ⊢ ((0 ∈ ℝ ∧ 1 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 1 ∧ 1 < 𝐵) → 0 < 𝐵)) | |
19 | 16, 17, 18 | mp3an12 1443 | . . . . . . . . . 10 ⊢ (𝐵 ∈ ℝ → ((0 < 1 ∧ 1 < 𝐵) → 0 < 𝐵)) |
20 | 15, 19 | mpani 692 | . . . . . . . . 9 ⊢ (𝐵 ∈ ℝ → (1 < 𝐵 → 0 < 𝐵)) |
21 | 20 | imp 407 | . . . . . . . 8 ⊢ ((𝐵 ∈ ℝ ∧ 1 < 𝐵) → 0 < 𝐵) |
22 | 21 | adantr 481 | . . . . . . 7 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 0 < 𝐵) |
23 | expgt0 13316 | . . . . . . 7 ⊢ ((𝐵 ∈ ℝ ∧ 𝑘 ∈ ℤ ∧ 0 < 𝐵) → 0 < (𝐵↑𝑘)) | |
24 | 12, 14, 22, 23 | syl3anc 1364 | . . . . . 6 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → 0 < (𝐵↑𝑘)) |
25 | 11, 24 | jca 512 | . . . . 5 ⊢ (((𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) |
26 | 25 | 3adantl1 1159 | . . . 4 ⊢ (((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) |
27 | ltrec1 11381 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 0 < 𝐴) ∧ ((𝐵↑𝑘) ∈ ℝ ∧ 0 < (𝐵↑𝑘))) → ((1 / 𝐴) < (𝐵↑𝑘) ↔ (1 / (𝐵↑𝑘)) < 𝐴)) | |
28 | 7, 26, 27 | syl2an2r 681 | . . 3 ⊢ (((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) ∧ 𝑘 ∈ ℕ) → ((1 / 𝐴) < (𝐵↑𝑘) ↔ (1 / (𝐵↑𝑘)) < 𝐴)) |
29 | 28 | rexbidva 3261 | . 2 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → (∃𝑘 ∈ ℕ (1 / 𝐴) < (𝐵↑𝑘) ↔ ∃𝑘 ∈ ℕ (1 / (𝐵↑𝑘)) < 𝐴)) |
30 | 5, 29 | mpbid 233 | 1 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐵 ∈ ℝ ∧ 1 < 𝐵) → ∃𝑘 ∈ ℕ (1 / (𝐵↑𝑘)) < 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 207 ∧ wa 396 ∧ w3a 1080 ∈ wcel 2083 ∃wrex 3108 class class class wbr 4968 (class class class)co 7023 ℝcr 10389 0cc0 10390 1c1 10391 < clt 10528 / cdiv 11151 ℕcn 11492 ℕ0cn0 11751 ℤcz 11835 ℝ+crp 12243 ↑cexp 13283 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1781 ax-4 1795 ax-5 1892 ax-6 1951 ax-7 1996 ax-8 2085 ax-9 2093 ax-10 2114 ax-11 2128 ax-12 2143 ax-13 2346 ax-ext 2771 ax-sep 5101 ax-nul 5108 ax-pow 5164 ax-pr 5228 ax-un 7326 ax-cnex 10446 ax-resscn 10447 ax-1cn 10448 ax-icn 10449 ax-addcl 10450 ax-addrcl 10451 ax-mulcl 10452 ax-mulrcl 10453 ax-mulcom 10454 ax-addass 10455 ax-mulass 10456 ax-distr 10457 ax-i2m1 10458 ax-1ne0 10459 ax-1rid 10460 ax-rnegex 10461 ax-rrecex 10462 ax-cnre 10463 ax-pre-lttri 10464 ax-pre-lttrn 10465 ax-pre-ltadd 10466 ax-pre-mulgt0 10467 ax-pre-sup 10468 |
This theorem depends on definitions: df-bi 208 df-an 397 df-or 843 df-3or 1081 df-3an 1082 df-tru 1528 df-ex 1766 df-nf 1770 df-sb 2045 df-mo 2578 df-eu 2614 df-clab 2778 df-cleq 2790 df-clel 2865 df-nfc 2937 df-ne 2987 df-nel 3093 df-ral 3112 df-rex 3113 df-reu 3114 df-rmo 3115 df-rab 3116 df-v 3442 df-sbc 3712 df-csb 3818 df-dif 3868 df-un 3870 df-in 3872 df-ss 3880 df-pss 3882 df-nul 4218 df-if 4388 df-pw 4461 df-sn 4479 df-pr 4481 df-tp 4483 df-op 4485 df-uni 4752 df-iun 4833 df-br 4969 df-opab 5031 df-mpt 5048 df-tr 5071 df-id 5355 df-eprel 5360 df-po 5369 df-so 5370 df-fr 5409 df-we 5411 df-xp 5456 df-rel 5457 df-cnv 5458 df-co 5459 df-dm 5460 df-rn 5461 df-res 5462 df-ima 5463 df-pred 6030 df-ord 6076 df-on 6077 df-lim 6078 df-suc 6079 df-iota 6196 df-fun 6234 df-fn 6235 df-f 6236 df-f1 6237 df-fo 6238 df-f1o 6239 df-fv 6240 df-riota 6984 df-ov 7026 df-oprab 7027 df-mpo 7028 df-om 7444 df-2nd 7553 df-wrecs 7805 df-recs 7867 df-rdg 7905 df-er 8146 df-en 8365 df-dom 8366 df-sdom 8367 df-sup 8759 df-inf 8760 df-pnf 10530 df-mnf 10531 df-xr 10532 df-ltxr 10533 df-le 10534 df-sub 10725 df-neg 10726 df-div 11152 df-nn 11493 df-n0 11752 df-z 11836 df-uz 12098 df-rp 12244 df-fl 13016 df-seq 13224 df-exp 13284 |
This theorem is referenced by: expnlbnd2 13449 opnmbllem 23889 opnmbllem0 34480 heiborlem7 34648 |
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