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Mirrors > Home > ILE Home > Th. List > apsqgt0 | GIF version |
Description: The square of a real number apart from zero is positive. (Contributed by Jim Kingdon, 7-Feb-2020.) |
Ref | Expression |
---|---|
apsqgt0 | ⊢ ((𝐴 ∈ ℝ ∧ 𝐴 # 0) → 0 < (𝐴 · 𝐴)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0re 7982 | . . . 4 ⊢ 0 ∈ ℝ | |
2 | reaplt 8570 | . . . 4 ⊢ ((𝐴 ∈ ℝ ∧ 0 ∈ ℝ) → (𝐴 # 0 ↔ (𝐴 < 0 ∨ 0 < 𝐴))) | |
3 | 1, 2 | mpan2 425 | . . 3 ⊢ (𝐴 ∈ ℝ → (𝐴 # 0 ↔ (𝐴 < 0 ∨ 0 < 𝐴))) |
4 | 3 | pm5.32i 454 | . 2 ⊢ ((𝐴 ∈ ℝ ∧ 𝐴 # 0) ↔ (𝐴 ∈ ℝ ∧ (𝐴 < 0 ∨ 0 < 𝐴))) |
5 | mullt0 8462 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 𝐴 < 0) ∧ (𝐴 ∈ ℝ ∧ 𝐴 < 0)) → 0 < (𝐴 · 𝐴)) | |
6 | 5 | anidms 397 | . . 3 ⊢ ((𝐴 ∈ ℝ ∧ 𝐴 < 0) → 0 < (𝐴 · 𝐴)) |
7 | mulgt0 8057 | . . . 4 ⊢ (((𝐴 ∈ ℝ ∧ 0 < 𝐴) ∧ (𝐴 ∈ ℝ ∧ 0 < 𝐴)) → 0 < (𝐴 · 𝐴)) | |
8 | 7 | anidms 397 | . . 3 ⊢ ((𝐴 ∈ ℝ ∧ 0 < 𝐴) → 0 < (𝐴 · 𝐴)) |
9 | 6, 8 | jaodan 798 | . 2 ⊢ ((𝐴 ∈ ℝ ∧ (𝐴 < 0 ∨ 0 < 𝐴)) → 0 < (𝐴 · 𝐴)) |
10 | 4, 9 | sylbi 121 | 1 ⊢ ((𝐴 ∈ ℝ ∧ 𝐴 # 0) → 0 < (𝐴 · 𝐴)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ↔ wb 105 ∨ wo 709 ∈ wcel 2160 class class class wbr 4018 (class class class)co 5892 ℝcr 7835 0cc0 7836 · cmul 7841 < clt 8017 # cap 8563 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 615 ax-in2 616 ax-io 710 ax-5 1458 ax-7 1459 ax-gen 1460 ax-ie1 1504 ax-ie2 1505 ax-8 1515 ax-10 1516 ax-11 1517 ax-i12 1518 ax-bndl 1520 ax-4 1521 ax-17 1537 ax-i9 1541 ax-ial 1545 ax-i5r 1546 ax-13 2162 ax-14 2163 ax-ext 2171 ax-sep 4136 ax-pow 4189 ax-pr 4224 ax-un 4448 ax-setind 4551 ax-cnex 7927 ax-resscn 7928 ax-1cn 7929 ax-1re 7930 ax-icn 7931 ax-addcl 7932 ax-addrcl 7933 ax-mulcl 7934 ax-mulrcl 7935 ax-addcom 7936 ax-mulcom 7937 ax-addass 7938 ax-mulass 7939 ax-distr 7940 ax-i2m1 7941 ax-0lt1 7942 ax-1rid 7943 ax-0id 7944 ax-rnegex 7945 ax-precex 7946 ax-cnre 7947 ax-pre-ltirr 7948 ax-pre-lttrn 7950 ax-pre-apti 7951 ax-pre-ltadd 7952 ax-pre-mulgt0 7953 |
This theorem depends on definitions: df-bi 117 df-3an 982 df-tru 1367 df-fal 1370 df-nf 1472 df-sb 1774 df-eu 2041 df-mo 2042 df-clab 2176 df-cleq 2182 df-clel 2185 df-nfc 2321 df-ne 2361 df-nel 2456 df-ral 2473 df-rex 2474 df-reu 2475 df-rab 2477 df-v 2754 df-sbc 2978 df-dif 3146 df-un 3148 df-in 3150 df-ss 3157 df-pw 3592 df-sn 3613 df-pr 3614 df-op 3616 df-uni 3825 df-br 4019 df-opab 4080 df-id 4308 df-xp 4647 df-rel 4648 df-cnv 4649 df-co 4650 df-dm 4651 df-iota 5193 df-fun 5234 df-fv 5240 df-riota 5848 df-ov 5895 df-oprab 5896 df-mpo 5897 df-pnf 8019 df-mnf 8020 df-ltxr 8022 df-sub 8155 df-neg 8156 df-reap 8557 df-ap 8564 |
This theorem is referenced by: msqge0 8598 recexaplem2 8634 msqznn 9378 sqgt0ap 10615 |
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