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Mirrors > Home > MPE Home > Th. List > relogbmul | Structured version Visualization version GIF version |
Description: The logarithm of the product of two positive real numbers is the sum of logarithms. Property 2 of [Cohen4] p. 361. (Contributed by Stefan O'Rear, 19-Sep-2014.) (Revised by AV, 29-May-2020.) |
Ref | Expression |
---|---|
relogbmul | ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (𝐵 logb (𝐴 · 𝐶)) = ((𝐵 logb 𝐴) + (𝐵 logb 𝐶))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | relogmul 25167 | . . . . 5 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (log‘(𝐴 · 𝐶)) = ((log‘𝐴) + (log‘𝐶))) | |
2 | 1 | adantl 484 | . . . 4 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (log‘(𝐴 · 𝐶)) = ((log‘𝐴) + (log‘𝐶))) |
3 | 2 | oveq1d 7163 | . . 3 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → ((log‘(𝐴 · 𝐶)) / (log‘𝐵)) = (((log‘𝐴) + (log‘𝐶)) / (log‘𝐵))) |
4 | relogcl 25151 | . . . . . 6 ⊢ (𝐴 ∈ ℝ+ → (log‘𝐴) ∈ ℝ) | |
5 | 4 | recnd 10661 | . . . . 5 ⊢ (𝐴 ∈ ℝ+ → (log‘𝐴) ∈ ℂ) |
6 | 5 | adantr 483 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (log‘𝐴) ∈ ℂ) |
7 | relogcl 25151 | . . . . . 6 ⊢ (𝐶 ∈ ℝ+ → (log‘𝐶) ∈ ℝ) | |
8 | 7 | recnd 10661 | . . . . 5 ⊢ (𝐶 ∈ ℝ+ → (log‘𝐶) ∈ ℂ) |
9 | 8 | adantl 484 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (log‘𝐶) ∈ ℂ) |
10 | eldifpr 4589 | . . . . . . . 8 ⊢ (𝐵 ∈ (ℂ ∖ {0, 1}) ↔ (𝐵 ∈ ℂ ∧ 𝐵 ≠ 0 ∧ 𝐵 ≠ 1)) | |
11 | 3simpa 1143 | . . . . . . . 8 ⊢ ((𝐵 ∈ ℂ ∧ 𝐵 ≠ 0 ∧ 𝐵 ≠ 1) → (𝐵 ∈ ℂ ∧ 𝐵 ≠ 0)) | |
12 | 10, 11 | sylbi 219 | . . . . . . 7 ⊢ (𝐵 ∈ (ℂ ∖ {0, 1}) → (𝐵 ∈ ℂ ∧ 𝐵 ≠ 0)) |
13 | logcl 25144 | . . . . . . 7 ⊢ ((𝐵 ∈ ℂ ∧ 𝐵 ≠ 0) → (log‘𝐵) ∈ ℂ) | |
14 | 12, 13 | syl 17 | . . . . . 6 ⊢ (𝐵 ∈ (ℂ ∖ {0, 1}) → (log‘𝐵) ∈ ℂ) |
15 | logccne0 25154 | . . . . . . 7 ⊢ ((𝐵 ∈ ℂ ∧ 𝐵 ≠ 0 ∧ 𝐵 ≠ 1) → (log‘𝐵) ≠ 0) | |
16 | 10, 15 | sylbi 219 | . . . . . 6 ⊢ (𝐵 ∈ (ℂ ∖ {0, 1}) → (log‘𝐵) ≠ 0) |
17 | 14, 16 | jca 514 | . . . . 5 ⊢ (𝐵 ∈ (ℂ ∖ {0, 1}) → ((log‘𝐵) ∈ ℂ ∧ (log‘𝐵) ≠ 0)) |
18 | 17 | adantr 483 | . . . 4 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → ((log‘𝐵) ∈ ℂ ∧ (log‘𝐵) ≠ 0)) |
19 | divdir 11315 | . . . 4 ⊢ (((log‘𝐴) ∈ ℂ ∧ (log‘𝐶) ∈ ℂ ∧ ((log‘𝐵) ∈ ℂ ∧ (log‘𝐵) ≠ 0)) → (((log‘𝐴) + (log‘𝐶)) / (log‘𝐵)) = (((log‘𝐴) / (log‘𝐵)) + ((log‘𝐶) / (log‘𝐵)))) | |
20 | 6, 9, 18, 19 | syl2an23an 1418 | . . 3 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (((log‘𝐴) + (log‘𝐶)) / (log‘𝐵)) = (((log‘𝐴) / (log‘𝐵)) + ((log‘𝐶) / (log‘𝐵)))) |
21 | 3, 20 | eqtrd 2854 | . 2 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → ((log‘(𝐴 · 𝐶)) / (log‘𝐵)) = (((log‘𝐴) / (log‘𝐵)) + ((log‘𝐶) / (log‘𝐵)))) |
22 | rpcn 12391 | . . . . 5 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ∈ ℂ) | |
23 | rpcn 12391 | . . . . 5 ⊢ (𝐶 ∈ ℝ+ → 𝐶 ∈ ℂ) | |
24 | mulcl 10613 | . . . . 5 ⊢ ((𝐴 ∈ ℂ ∧ 𝐶 ∈ ℂ) → (𝐴 · 𝐶) ∈ ℂ) | |
25 | 22, 23, 24 | syl2an 597 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (𝐴 · 𝐶) ∈ ℂ) |
26 | 22 | adantr 483 | . . . . 5 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐴 ∈ ℂ) |
27 | 23 | adantl 484 | . . . . 5 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐶 ∈ ℂ) |
28 | rpne0 12397 | . . . . . 6 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ≠ 0) | |
29 | 28 | adantr 483 | . . . . 5 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐴 ≠ 0) |
30 | rpne0 12397 | . . . . . 6 ⊢ (𝐶 ∈ ℝ+ → 𝐶 ≠ 0) | |
31 | 30 | adantl 484 | . . . . 5 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐶 ≠ 0) |
32 | 26, 27, 29, 31 | mulne0d 11284 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (𝐴 · 𝐶) ≠ 0) |
33 | eldifsn 4711 | . . . 4 ⊢ ((𝐴 · 𝐶) ∈ (ℂ ∖ {0}) ↔ ((𝐴 · 𝐶) ∈ ℂ ∧ (𝐴 · 𝐶) ≠ 0)) | |
34 | 25, 32, 33 | sylanbrc 585 | . . 3 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → (𝐴 · 𝐶) ∈ (ℂ ∖ {0})) |
35 | logbval 25336 | . . 3 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 · 𝐶) ∈ (ℂ ∖ {0})) → (𝐵 logb (𝐴 · 𝐶)) = ((log‘(𝐴 · 𝐶)) / (log‘𝐵))) | |
36 | 34, 35 | sylan2 594 | . 2 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (𝐵 logb (𝐴 · 𝐶)) = ((log‘(𝐴 · 𝐶)) / (log‘𝐵))) |
37 | rpcndif0 12400 | . . . . 5 ⊢ (𝐴 ∈ ℝ+ → 𝐴 ∈ (ℂ ∖ {0})) | |
38 | 37 | adantr 483 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐴 ∈ (ℂ ∖ {0})) |
39 | logbval 25336 | . . . 4 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ 𝐴 ∈ (ℂ ∖ {0})) → (𝐵 logb 𝐴) = ((log‘𝐴) / (log‘𝐵))) | |
40 | 38, 39 | sylan2 594 | . . 3 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (𝐵 logb 𝐴) = ((log‘𝐴) / (log‘𝐵))) |
41 | rpcndif0 12400 | . . . . 5 ⊢ (𝐶 ∈ ℝ+ → 𝐶 ∈ (ℂ ∖ {0})) | |
42 | 41 | adantl 484 | . . . 4 ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+) → 𝐶 ∈ (ℂ ∖ {0})) |
43 | logbval 25336 | . . . 4 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ 𝐶 ∈ (ℂ ∖ {0})) → (𝐵 logb 𝐶) = ((log‘𝐶) / (log‘𝐵))) | |
44 | 42, 43 | sylan2 594 | . . 3 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (𝐵 logb 𝐶) = ((log‘𝐶) / (log‘𝐵))) |
45 | 40, 44 | oveq12d 7166 | . 2 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → ((𝐵 logb 𝐴) + (𝐵 logb 𝐶)) = (((log‘𝐴) / (log‘𝐵)) + ((log‘𝐶) / (log‘𝐵)))) |
46 | 21, 36, 45 | 3eqtr4d 2864 | 1 ⊢ ((𝐵 ∈ (ℂ ∖ {0, 1}) ∧ (𝐴 ∈ ℝ+ ∧ 𝐶 ∈ ℝ+)) → (𝐵 logb (𝐴 · 𝐶)) = ((𝐵 logb 𝐴) + (𝐵 logb 𝐶))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 398 ∧ w3a 1082 = wceq 1531 ∈ wcel 2108 ≠ wne 3014 ∖ cdif 3931 {csn 4559 {cpr 4561 ‘cfv 6348 (class class class)co 7148 ℂcc 10527 0cc0 10529 1c1 10530 + caddc 10532 · cmul 10534 / cdiv 11289 ℝ+crp 12381 logclog 25130 logb clogb 25334 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1905 ax-6 1964 ax-7 2009 ax-8 2110 ax-9 2118 ax-10 2139 ax-11 2154 ax-12 2170 ax-ext 2791 ax-rep 5181 ax-sep 5194 ax-nul 5201 ax-pow 5257 ax-pr 5320 ax-un 7453 ax-inf2 9096 ax-cnex 10585 ax-resscn 10586 ax-1cn 10587 ax-icn 10588 ax-addcl 10589 ax-addrcl 10590 ax-mulcl 10591 ax-mulrcl 10592 ax-mulcom 10593 ax-addass 10594 ax-mulass 10595 ax-distr 10596 ax-i2m1 10597 ax-1ne0 10598 ax-1rid 10599 ax-rnegex 10600 ax-rrecex 10601 ax-cnre 10602 ax-pre-lttri 10603 ax-pre-lttrn 10604 ax-pre-ltadd 10605 ax-pre-mulgt0 10606 ax-pre-sup 10607 ax-addf 10608 ax-mulf 10609 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1083 df-3an 1084 df-tru 1534 df-fal 1544 df-ex 1775 df-nf 1779 df-sb 2064 df-mo 2616 df-eu 2648 df-clab 2798 df-cleq 2812 df-clel 2891 df-nfc 2961 df-ne 3015 df-nel 3122 df-ral 3141 df-rex 3142 df-reu 3143 df-rmo 3144 df-rab 3145 df-v 3495 df-sbc 3771 df-csb 3882 df-dif 3937 df-un 3939 df-in 3941 df-ss 3950 df-pss 3952 df-nul 4290 df-if 4466 df-pw 4539 df-sn 4560 df-pr 4562 df-tp 4564 df-op 4566 df-uni 4831 df-int 4868 df-iun 4912 df-iin 4913 df-br 5058 df-opab 5120 df-mpt 5138 df-tr 5164 df-id 5453 df-eprel 5458 df-po 5467 df-so 5468 df-fr 5507 df-se 5508 df-we 5509 df-xp 5554 df-rel 5555 df-cnv 5556 df-co 5557 df-dm 5558 df-rn 5559 df-res 5560 df-ima 5561 df-pred 6141 df-ord 6187 df-on 6188 df-lim 6189 df-suc 6190 df-iota 6307 df-fun 6350 df-fn 6351 df-f 6352 df-f1 6353 df-fo 6354 df-f1o 6355 df-fv 6356 df-isom 6357 df-riota 7106 df-ov 7151 df-oprab 7152 df-mpo 7153 df-of 7401 df-om 7573 df-1st 7681 df-2nd 7682 df-supp 7823 df-wrecs 7939 df-recs 8000 df-rdg 8038 df-1o 8094 df-2o 8095 df-oadd 8098 df-er 8281 df-map 8400 df-pm 8401 df-ixp 8454 df-en 8502 df-dom 8503 df-sdom 8504 df-fin 8505 df-fsupp 8826 df-fi 8867 df-sup 8898 df-inf 8899 df-oi 8966 df-card 9360 df-pnf 10669 df-mnf 10670 df-xr 10671 df-ltxr 10672 df-le 10673 df-sub 10864 df-neg 10865 df-div 11290 df-nn 11631 df-2 11692 df-3 11693 df-4 11694 df-5 11695 df-6 11696 df-7 11697 df-8 11698 df-9 11699 df-n0 11890 df-z 11974 df-dec 12091 df-uz 12236 df-q 12341 df-rp 12382 df-xneg 12499 df-xadd 12500 df-xmul 12501 df-ioo 12734 df-ioc 12735 df-ico 12736 df-icc 12737 df-fz 12885 df-fzo 13026 df-fl 13154 df-mod 13230 df-seq 13362 df-exp 13422 df-fac 13626 df-bc 13655 df-hash 13683 df-shft 14418 df-cj 14450 df-re 14451 df-im 14452 df-sqrt 14586 df-abs 14587 df-limsup 14820 df-clim 14837 df-rlim 14838 df-sum 15035 df-ef 15413 df-sin 15415 df-cos 15416 df-pi 15418 df-struct 16477 df-ndx 16478 df-slot 16479 df-base 16481 df-sets 16482 df-ress 16483 df-plusg 16570 df-mulr 16571 df-starv 16572 df-sca 16573 df-vsca 16574 df-ip 16575 df-tset 16576 df-ple 16577 df-ds 16579 df-unif 16580 df-hom 16581 df-cco 16582 df-rest 16688 df-topn 16689 df-0g 16707 df-gsum 16708 df-topgen 16709 df-pt 16710 df-prds 16713 df-xrs 16767 df-qtop 16772 df-imas 16773 df-xps 16775 df-mre 16849 df-mrc 16850 df-acs 16852 df-mgm 17844 df-sgrp 17893 df-mnd 17904 df-submnd 17949 df-mulg 18217 df-cntz 18439 df-cmn 18900 df-psmet 20529 df-xmet 20530 df-met 20531 df-bl 20532 df-mopn 20533 df-fbas 20534 df-fg 20535 df-cnfld 20538 df-top 21494 df-topon 21511 df-topsp 21533 df-bases 21546 df-cld 21619 df-ntr 21620 df-cls 21621 df-nei 21698 df-lp 21736 df-perf 21737 df-cn 21827 df-cnp 21828 df-haus 21915 df-tx 22162 df-hmeo 22355 df-fil 22446 df-fm 22538 df-flim 22539 df-flf 22540 df-xms 22922 df-ms 22923 df-tms 22924 df-cncf 23478 df-limc 24456 df-dv 24457 df-log 25132 df-logb 25335 |
This theorem is referenced by: relogbmulexp 25348 blennnt2 44640 |
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