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Mirrors > Home > ILE Home > Th. List > prodge0 | GIF version |
Description: Infer that a multiplicand is nonnegative from a positive multiplier and nonnegative product. (Contributed by NM, 2-Jul-2005.) (Revised by Mario Carneiro, 27-May-2016.) |
Ref | Expression |
---|---|
prodge0 | ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 ≤ (𝐴 · 𝐵))) → 0 ≤ 𝐵) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simpll 496 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 𝐴 ∈ ℝ) | |
2 | simplr 497 | . . . . . . . . 9 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 𝐵 ∈ ℝ) | |
3 | 2 | renegcld 7858 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → -𝐵 ∈ ℝ) |
4 | simprl 498 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 0 < 𝐴) | |
5 | simprr 499 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 0 < -𝐵) | |
6 | 1, 3, 4, 5 | mulgt0d 7606 | . . . . . . 7 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 0 < (𝐴 · -𝐵)) |
7 | 1 | recnd 7516 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 𝐴 ∈ ℂ) |
8 | 2 | recnd 7516 | . . . . . . . 8 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 𝐵 ∈ ℂ) |
9 | 7, 8 | mulneg2d 7890 | . . . . . . 7 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → (𝐴 · -𝐵) = -(𝐴 · 𝐵)) |
10 | 6, 9 | breqtrd 3869 | . . . . . 6 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 < -𝐵)) → 0 < -(𝐴 · 𝐵)) |
11 | 10 | expr 367 | . . . . 5 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (0 < -𝐵 → 0 < -(𝐴 · 𝐵))) |
12 | simplr 497 | . . . . . 6 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → 𝐵 ∈ ℝ) | |
13 | 12 | lt0neg1d 7993 | . . . . 5 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (𝐵 < 0 ↔ 0 < -𝐵)) |
14 | simpll 496 | . . . . . . 7 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → 𝐴 ∈ ℝ) | |
15 | 14, 12 | remulcld 7518 | . . . . . 6 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (𝐴 · 𝐵) ∈ ℝ) |
16 | 15 | lt0neg1d 7993 | . . . . 5 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → ((𝐴 · 𝐵) < 0 ↔ 0 < -(𝐴 · 𝐵))) |
17 | 11, 13, 16 | 3imtr4d 201 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (𝐵 < 0 → (𝐴 · 𝐵) < 0)) |
18 | 17 | con3d 596 | . . 3 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (¬ (𝐴 · 𝐵) < 0 → ¬ 𝐵 < 0)) |
19 | 0red 7489 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → 0 ∈ ℝ) | |
20 | 19, 15 | lenltd 7601 | . . 3 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (0 ≤ (𝐴 · 𝐵) ↔ ¬ (𝐴 · 𝐵) < 0)) |
21 | 19, 12 | lenltd 7601 | . . 3 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (0 ≤ 𝐵 ↔ ¬ 𝐵 < 0)) |
22 | 18, 20, 21 | 3imtr4d 201 | . 2 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ 0 < 𝐴) → (0 ≤ (𝐴 · 𝐵) → 0 ≤ 𝐵)) |
23 | 22 | impr 371 | 1 ⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (0 < 𝐴 ∧ 0 ≤ (𝐴 · 𝐵))) → 0 ≤ 𝐵) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 102 ∈ wcel 1438 class class class wbr 3845 (class class class)co 5652 ℝcr 7349 0cc0 7350 · cmul 7355 < clt 7522 ≤ cle 7523 -cneg 7654 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 579 ax-in2 580 ax-io 665 ax-5 1381 ax-7 1382 ax-gen 1383 ax-ie1 1427 ax-ie2 1428 ax-8 1440 ax-10 1441 ax-11 1442 ax-i12 1443 ax-bndl 1444 ax-4 1445 ax-13 1449 ax-14 1450 ax-17 1464 ax-i9 1468 ax-ial 1472 ax-i5r 1473 ax-ext 2070 ax-sep 3957 ax-pow 4009 ax-pr 4036 ax-un 4260 ax-setind 4353 ax-cnex 7436 ax-resscn 7437 ax-1cn 7438 ax-1re 7439 ax-icn 7440 ax-addcl 7441 ax-addrcl 7442 ax-mulcl 7443 ax-mulrcl 7444 ax-addcom 7445 ax-mulcom 7446 ax-addass 7447 ax-distr 7449 ax-i2m1 7450 ax-0id 7453 ax-rnegex 7454 ax-cnre 7456 ax-pre-ltadd 7461 ax-pre-mulgt0 7462 |
This theorem depends on definitions: df-bi 115 df-3an 926 df-tru 1292 df-fal 1295 df-nf 1395 df-sb 1693 df-eu 1951 df-mo 1952 df-clab 2075 df-cleq 2081 df-clel 2084 df-nfc 2217 df-ne 2256 df-nel 2351 df-ral 2364 df-rex 2365 df-reu 2366 df-rab 2368 df-v 2621 df-sbc 2841 df-dif 3001 df-un 3003 df-in 3005 df-ss 3012 df-pw 3431 df-sn 3452 df-pr 3453 df-op 3455 df-uni 3654 df-br 3846 df-opab 3900 df-id 4120 df-xp 4444 df-rel 4445 df-cnv 4446 df-co 4447 df-dm 4448 df-iota 4980 df-fun 5017 df-fv 5023 df-riota 5608 df-ov 5655 df-oprab 5656 df-mpt2 5657 df-pnf 7524 df-mnf 7525 df-xr 7526 df-ltxr 7527 df-le 7528 df-sub 7655 df-neg 7656 |
This theorem is referenced by: prodge02 8316 prodge0i 8370 oexpneg 11155 evennn02n 11160 |
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