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Mirrors > Home > MPE Home > Th. List > axmulgt0 | Structured version Visualization version GIF version |
Description: The product of two positive reals is positive. Axiom 21 of 22 for real and complex numbers, derived from ZF set theory. (This restates ax-pre-mulgt0 11230 with ordering on the extended reals.) (Contributed by NM, 13-Oct-2005.) |
Ref | Expression |
---|---|
axmulgt0 | ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 𝐴 ∧ 0 < 𝐵) → 0 < (𝐴 · 𝐵))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-pre-mulgt0 11230 | . 2 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵) → 0 <ℝ (𝐴 · 𝐵))) | |
2 | 0re 11261 | . . . 4 ⊢ 0 ∈ ℝ | |
3 | ltxrlt 11329 | . . . 4 ⊢ ((0 ∈ ℝ ∧ 𝐴 ∈ ℝ) → (0 < 𝐴 ↔ 0 <ℝ 𝐴)) | |
4 | 2, 3 | mpan 690 | . . 3 ⊢ (𝐴 ∈ ℝ → (0 < 𝐴 ↔ 0 <ℝ 𝐴)) |
5 | ltxrlt 11329 | . . . 4 ⊢ ((0 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (0 < 𝐵 ↔ 0 <ℝ 𝐵)) | |
6 | 2, 5 | mpan 690 | . . 3 ⊢ (𝐵 ∈ ℝ → (0 < 𝐵 ↔ 0 <ℝ 𝐵)) |
7 | 4, 6 | bi2anan9 638 | . 2 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 𝐴 ∧ 0 < 𝐵) ↔ (0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵))) |
8 | remulcl 11238 | . . 3 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴 · 𝐵) ∈ ℝ) | |
9 | ltxrlt 11329 | . . 3 ⊢ ((0 ∈ ℝ ∧ (𝐴 · 𝐵) ∈ ℝ) → (0 < (𝐴 · 𝐵) ↔ 0 <ℝ (𝐴 · 𝐵))) | |
10 | 2, 8, 9 | sylancr 587 | . 2 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (0 < (𝐴 · 𝐵) ↔ 0 <ℝ (𝐴 · 𝐵))) |
11 | 1, 7, 10 | 3imtr4d 294 | 1 ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 < 𝐴 ∧ 0 < 𝐵) → 0 < (𝐴 · 𝐵))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 ∈ wcel 2106 class class class wbr 5148 (class class class)co 7431 ℝcr 11152 0cc0 11153 <ℝ cltrr 11157 · cmul 11158 < clt 11293 |
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 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-10 2139 ax-11 2155 ax-12 2175 ax-ext 2706 ax-sep 5302 ax-nul 5312 ax-pow 5371 ax-pr 5438 ax-un 7754 ax-resscn 11210 ax-1cn 11211 ax-addrcl 11214 ax-mulrcl 11216 ax-rnegex 11224 ax-cnre 11226 ax-pre-mulgt0 11230 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-nf 1781 df-sb 2063 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2727 df-clel 2814 df-nfc 2890 df-ne 2939 df-nel 3045 df-ral 3060 df-rex 3069 df-rab 3434 df-v 3480 df-sbc 3792 df-csb 3909 df-dif 3966 df-un 3968 df-in 3970 df-ss 3980 df-nul 4340 df-if 4532 df-pw 4607 df-sn 4632 df-pr 4634 df-op 4638 df-uni 4913 df-br 5149 df-opab 5211 df-mpt 5232 df-id 5583 df-xp 5695 df-rel 5696 df-cnv 5697 df-co 5698 df-dm 5699 df-rn 5700 df-res 5701 df-ima 5702 df-iota 6516 df-fun 6565 df-fn 6566 df-f 6567 df-f1 6568 df-fo 6569 df-f1o 6570 df-fv 6571 df-er 8744 df-en 8985 df-dom 8986 df-sdom 8987 df-pnf 11295 df-mnf 11296 df-ltxr 11298 |
This theorem is referenced by: mulgt0 11336 mulgt0i 11391 sin02gt0 16225 sinq12gt0 26564 |
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