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Mirrors > Home > MPE Home > Th. List > recgt0ii | Structured version Visualization version GIF version |
Description: The reciprocal of a positive number is positive. Exercise 4 of [Apostol] p. 21. (Contributed by NM, 15-May-1999.) |
Ref | Expression |
---|---|
ltplus1.1 | ⊢ 𝐴 ∈ ℝ |
recgt0i.2 | ⊢ 0 < 𝐴 |
Ref | Expression |
---|---|
recgt0ii | ⊢ 0 < (1 / 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-1cn 10594 | . . . . 5 ⊢ 1 ∈ ℂ | |
2 | ltplus1.1 | . . . . . 6 ⊢ 𝐴 ∈ ℝ | |
3 | 2 | recni 10654 | . . . . 5 ⊢ 𝐴 ∈ ℂ |
4 | ax-1ne0 10605 | . . . . 5 ⊢ 1 ≠ 0 | |
5 | recgt0i.2 | . . . . . 6 ⊢ 0 < 𝐴 | |
6 | 2, 5 | gt0ne0ii 11175 | . . . . 5 ⊢ 𝐴 ≠ 0 |
7 | 1, 3, 4, 6 | divne0i 11387 | . . . 4 ⊢ (1 / 𝐴) ≠ 0 |
8 | 7 | nesymi 3073 | . . 3 ⊢ ¬ 0 = (1 / 𝐴) |
9 | 0lt1 11161 | . . . . 5 ⊢ 0 < 1 | |
10 | 0re 10642 | . . . . . 6 ⊢ 0 ∈ ℝ | |
11 | 1re 10640 | . . . . . 6 ⊢ 1 ∈ ℝ | |
12 | 10, 11 | ltnsymi 10758 | . . . . 5 ⊢ (0 < 1 → ¬ 1 < 0) |
13 | 9, 12 | ax-mp 5 | . . . 4 ⊢ ¬ 1 < 0 |
14 | 2, 6 | rereccli 11404 | . . . . . . . . 9 ⊢ (1 / 𝐴) ∈ ℝ |
15 | 14 | renegcli 10946 | . . . . . . . 8 ⊢ -(1 / 𝐴) ∈ ℝ |
16 | 15, 2 | mulgt0i 10771 | . . . . . . 7 ⊢ ((0 < -(1 / 𝐴) ∧ 0 < 𝐴) → 0 < (-(1 / 𝐴) · 𝐴)) |
17 | 5, 16 | mpan2 689 | . . . . . 6 ⊢ (0 < -(1 / 𝐴) → 0 < (-(1 / 𝐴) · 𝐴)) |
18 | 14 | recni 10654 | . . . . . . . 8 ⊢ (1 / 𝐴) ∈ ℂ |
19 | 18, 3 | mulneg1i 11085 | . . . . . . 7 ⊢ (-(1 / 𝐴) · 𝐴) = -((1 / 𝐴) · 𝐴) |
20 | 3, 6 | recidi 11370 | . . . . . . . . 9 ⊢ (𝐴 · (1 / 𝐴)) = 1 |
21 | 3, 18, 20 | mulcomli 10649 | . . . . . . . 8 ⊢ ((1 / 𝐴) · 𝐴) = 1 |
22 | 21 | negeqi 10878 | . . . . . . 7 ⊢ -((1 / 𝐴) · 𝐴) = -1 |
23 | 19, 22 | eqtri 2844 | . . . . . 6 ⊢ (-(1 / 𝐴) · 𝐴) = -1 |
24 | 17, 23 | breqtrdi 5106 | . . . . 5 ⊢ (0 < -(1 / 𝐴) → 0 < -1) |
25 | lt0neg1 11145 | . . . . . 6 ⊢ ((1 / 𝐴) ∈ ℝ → ((1 / 𝐴) < 0 ↔ 0 < -(1 / 𝐴))) | |
26 | 14, 25 | ax-mp 5 | . . . . 5 ⊢ ((1 / 𝐴) < 0 ↔ 0 < -(1 / 𝐴)) |
27 | lt0neg1 11145 | . . . . . 6 ⊢ (1 ∈ ℝ → (1 < 0 ↔ 0 < -1)) | |
28 | 11, 27 | ax-mp 5 | . . . . 5 ⊢ (1 < 0 ↔ 0 < -1) |
29 | 24, 26, 28 | 3imtr4i 294 | . . . 4 ⊢ ((1 / 𝐴) < 0 → 1 < 0) |
30 | 13, 29 | mto 199 | . . 3 ⊢ ¬ (1 / 𝐴) < 0 |
31 | 8, 30 | pm3.2ni 877 | . 2 ⊢ ¬ (0 = (1 / 𝐴) ∨ (1 / 𝐴) < 0) |
32 | axlttri 10711 | . . 3 ⊢ ((0 ∈ ℝ ∧ (1 / 𝐴) ∈ ℝ) → (0 < (1 / 𝐴) ↔ ¬ (0 = (1 / 𝐴) ∨ (1 / 𝐴) < 0))) | |
33 | 10, 14, 32 | mp2an 690 | . 2 ⊢ (0 < (1 / 𝐴) ↔ ¬ (0 = (1 / 𝐴) ∨ (1 / 𝐴) < 0)) |
34 | 31, 33 | mpbir 233 | 1 ⊢ 0 < (1 / 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 208 ∨ wo 843 = wceq 1533 ∈ wcel 2110 class class class wbr 5065 (class class class)co 7155 ℝcr 10535 0cc0 10536 1c1 10537 · cmul 10541 < clt 10674 -cneg 10870 / cdiv 11296 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1907 ax-6 1966 ax-7 2011 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2157 ax-12 2173 ax-ext 2793 ax-sep 5202 ax-nul 5209 ax-pow 5265 ax-pr 5329 ax-un 7460 ax-resscn 10593 ax-1cn 10594 ax-icn 10595 ax-addcl 10596 ax-addrcl 10597 ax-mulcl 10598 ax-mulrcl 10599 ax-mulcom 10600 ax-addass 10601 ax-mulass 10602 ax-distr 10603 ax-i2m1 10604 ax-1ne0 10605 ax-1rid 10606 ax-rnegex 10607 ax-rrecex 10608 ax-cnre 10609 ax-pre-lttri 10610 ax-pre-lttrn 10611 ax-pre-ltadd 10612 ax-pre-mulgt0 10613 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1536 df-ex 1777 df-nf 1781 df-sb 2066 df-mo 2618 df-eu 2650 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3496 df-sbc 3772 df-csb 3883 df-dif 3938 df-un 3940 df-in 3942 df-ss 3951 df-nul 4291 df-if 4467 df-pw 4540 df-sn 4567 df-pr 4569 df-op 4573 df-uni 4838 df-br 5066 df-opab 5128 df-mpt 5146 df-id 5459 df-po 5473 df-so 5474 df-xp 5560 df-rel 5561 df-cnv 5562 df-co 5563 df-dm 5564 df-rn 5565 df-res 5566 df-ima 5567 df-iota 6313 df-fun 6356 df-fn 6357 df-f 6358 df-f1 6359 df-fo 6360 df-f1o 6361 df-fv 6362 df-riota 7113 df-ov 7158 df-oprab 7159 df-mpo 7160 df-er 8288 df-en 8509 df-dom 8510 df-sdom 8511 df-pnf 10676 df-mnf 10677 df-xr 10678 df-ltxr 10679 df-le 10680 df-sub 10871 df-neg 10872 df-div 11297 |
This theorem is referenced by: halfgt0 11852 0.999... 15236 sincos2sgn 15546 rpnnen2lem3 15568 rpnnen2lem4 15569 rpnnen2lem9 15574 pcoass 23627 log2tlbnd 25522 stoweidlem34 42318 stoweidlem59 42343 |
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