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Mirrors > Home > ILE Home > Th. List > even2n | GIF version |
Description: An integer is even iff it is twice another integer. (Contributed by AV, 25-Jun-2020.) |
Ref | Expression |
---|---|
even2n | ⊢ (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | evenelz 11600 | . 2 ⊢ (2 ∥ 𝑁 → 𝑁 ∈ ℤ) | |
2 | 2z 9106 | . . . . . . 7 ⊢ 2 ∈ ℤ | |
3 | 2 | a1i 9 | . . . . . 6 ⊢ (𝑛 ∈ ℤ → 2 ∈ ℤ) |
4 | id 19 | . . . . . 6 ⊢ (𝑛 ∈ ℤ → 𝑛 ∈ ℤ) | |
5 | 3, 4 | zmulcld 9203 | . . . . 5 ⊢ (𝑛 ∈ ℤ → (2 · 𝑛) ∈ ℤ) |
6 | 5 | adantr 274 | . . . 4 ⊢ ((𝑛 ∈ ℤ ∧ (2 · 𝑛) = 𝑁) → (2 · 𝑛) ∈ ℤ) |
7 | eleq1 2203 | . . . . 5 ⊢ ((2 · 𝑛) = 𝑁 → ((2 · 𝑛) ∈ ℤ ↔ 𝑁 ∈ ℤ)) | |
8 | 7 | adantl 275 | . . . 4 ⊢ ((𝑛 ∈ ℤ ∧ (2 · 𝑛) = 𝑁) → ((2 · 𝑛) ∈ ℤ ↔ 𝑁 ∈ ℤ)) |
9 | 6, 8 | mpbid 146 | . . 3 ⊢ ((𝑛 ∈ ℤ ∧ (2 · 𝑛) = 𝑁) → 𝑁 ∈ ℤ) |
10 | 9 | rexlimiva 2547 | . 2 ⊢ (∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁 → 𝑁 ∈ ℤ) |
11 | divides 11531 | . . . 4 ⊢ ((2 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (𝑛 · 2) = 𝑁)) | |
12 | zcn 9083 | . . . . . . 7 ⊢ (𝑛 ∈ ℤ → 𝑛 ∈ ℂ) | |
13 | 2cnd 8817 | . . . . . . 7 ⊢ (𝑛 ∈ ℤ → 2 ∈ ℂ) | |
14 | 12, 13 | mulcomd 7811 | . . . . . 6 ⊢ (𝑛 ∈ ℤ → (𝑛 · 2) = (2 · 𝑛)) |
15 | 14 | eqeq1d 2149 | . . . . 5 ⊢ (𝑛 ∈ ℤ → ((𝑛 · 2) = 𝑁 ↔ (2 · 𝑛) = 𝑁)) |
16 | 15 | rexbiia 2453 | . . . 4 ⊢ (∃𝑛 ∈ ℤ (𝑛 · 2) = 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁) |
17 | 11, 16 | syl6bb 195 | . . 3 ⊢ ((2 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁)) |
18 | 2, 17 | mpan 421 | . 2 ⊢ (𝑁 ∈ ℤ → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁)) |
19 | 1, 10, 18 | pm5.21nii 694 | 1 ⊢ (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁) |
Colors of variables: wff set class |
Syntax hints: ∧ wa 103 ↔ wb 104 = wceq 1332 ∈ wcel 1481 ∃wrex 2418 class class class wbr 3937 (class class class)co 5782 · cmul 7649 2c2 8795 ℤcz 9078 ∥ cdvds 11529 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1424 ax-7 1425 ax-gen 1426 ax-ie1 1470 ax-ie2 1471 ax-8 1483 ax-10 1484 ax-11 1485 ax-i12 1486 ax-bndl 1487 ax-4 1488 ax-13 1492 ax-14 1493 ax-17 1507 ax-i9 1511 ax-ial 1515 ax-i5r 1516 ax-ext 2122 ax-sep 4054 ax-pow 4106 ax-pr 4139 ax-un 4363 ax-setind 4460 ax-cnex 7735 ax-resscn 7736 ax-1cn 7737 ax-1re 7738 ax-icn 7739 ax-addcl 7740 ax-addrcl 7741 ax-mulcl 7742 ax-mulrcl 7743 ax-addcom 7744 ax-mulcom 7745 ax-addass 7746 ax-mulass 7747 ax-distr 7748 ax-i2m1 7749 ax-0lt1 7750 ax-1rid 7751 ax-0id 7752 ax-rnegex 7753 ax-cnre 7755 ax-pre-ltirr 7756 ax-pre-ltwlin 7757 ax-pre-lttrn 7758 ax-pre-ltadd 7760 |
This theorem depends on definitions: df-bi 116 df-3or 964 df-3an 965 df-tru 1335 df-fal 1338 df-nf 1438 df-sb 1737 df-eu 2003 df-mo 2004 df-clab 2127 df-cleq 2133 df-clel 2136 df-nfc 2271 df-ne 2310 df-nel 2405 df-ral 2422 df-rex 2423 df-reu 2424 df-rab 2426 df-v 2691 df-sbc 2914 df-dif 3078 df-un 3080 df-in 3082 df-ss 3089 df-pw 3517 df-sn 3538 df-pr 3539 df-op 3541 df-uni 3745 df-int 3780 df-br 3938 df-opab 3998 df-id 4223 df-xp 4553 df-rel 4554 df-cnv 4555 df-co 4556 df-dm 4557 df-iota 5096 df-fun 5133 df-fv 5139 df-riota 5738 df-ov 5785 df-oprab 5786 df-mpo 5787 df-pnf 7826 df-mnf 7827 df-xr 7828 df-ltxr 7829 df-le 7830 df-sub 7959 df-neg 7960 df-inn 8745 df-2 8803 df-n0 9002 df-z 9079 df-dvds 11530 |
This theorem is referenced by: evennn02n 11615 evennn2n 11616 m1expe 11632 |
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