rprelogbdiv - Intuitionistic Logic Explorer

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Theorem rprelogbdiv 14378

Description: The logarithm of the quotient of two positive real numbers is the difference of logarithms. Property 3 of [Cohen4] p. 361. (Contributed by AV, 29-May-2020.)

**Assertion**
Ref	Expression
rprelogbdiv	⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b (𝐴 / 𝐶)) = ((𝐵 log_b 𝐴) − (𝐵 log_b 𝐶)))

**Proof of Theorem rprelogbdiv**
Step	Hyp	Ref	Expression
1		neg1rr 9025	. . 3 ⊢ -1 ∈ ℝ
2		rprelogbmulexp 14377	. . 3 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺ ∧ -1 ∈ ℝ)) → (𝐵 log_b (𝐴 · (𝐶↑_𝑐-1))) = ((𝐵 log_b 𝐴) + (-1 · (𝐵 log_b 𝐶))))
3	1, 2	mp3anr3 1336	. 2 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b (𝐴 · (𝐶↑_𝑐-1))) = ((𝐵 log_b 𝐴) + (-1 · (𝐵 log_b 𝐶))))
4		rpcn 9662	. . . . . . 7 ⊢ (𝐴 ∈ ℝ⁺ → 𝐴 ∈ ℂ)
5	4	adantr 276	. . . . . 6 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → 𝐴 ∈ ℂ)
6		rpcn 9662	. . . . . . 7 ⊢ (𝐶 ∈ ℝ⁺ → 𝐶 ∈ ℂ)
7	6	adantl 277	. . . . . 6 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → 𝐶 ∈ ℂ)
8		rpap0 9670	. . . . . . 7 ⊢ (𝐶 ∈ ℝ⁺ → 𝐶 # 0)
9	8	adantl 277	. . . . . 6 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → 𝐶 # 0)
10	5, 7, 9	divrecapd 8750	. . . . 5 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → (𝐴 / 𝐶) = (𝐴 · (1 / 𝐶)))
11		ax-1cn 7904	. . . . . . . . 9 ⊢ 1 ∈ ℂ
12		rpcxpneg 14331	. . . . . . . . 9 ⊢ ((𝐶 ∈ ℝ⁺ ∧ 1 ∈ ℂ) → (𝐶↑_𝑐-1) = (1 / (𝐶↑_𝑐1)))
13	11, 12	mpan2 425	. . . . . . . 8 ⊢ (𝐶 ∈ ℝ⁺ → (𝐶↑_𝑐-1) = (1 / (𝐶↑_𝑐1)))
14		rpcxp1 14323	. . . . . . . . 9 ⊢ (𝐶 ∈ ℝ⁺ → (𝐶↑_𝑐1) = 𝐶)
15	14	oveq2d 5891	. . . . . . . 8 ⊢ (𝐶 ∈ ℝ⁺ → (1 / (𝐶↑_𝑐1)) = (1 / 𝐶))
16	13, 15	eqtrd 2210	. . . . . . 7 ⊢ (𝐶 ∈ ℝ⁺ → (𝐶↑_𝑐-1) = (1 / 𝐶))
17	16	adantl 277	. . . . . 6 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → (𝐶↑_𝑐-1) = (1 / 𝐶))
18	17	oveq2d 5891	. . . . 5 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → (𝐴 · (𝐶↑_𝑐-1)) = (𝐴 · (1 / 𝐶)))
19	10, 18	eqtr4d 2213	. . . 4 ⊢ ((𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺) → (𝐴 / 𝐶) = (𝐴 · (𝐶↑_𝑐-1)))
20	19	adantl 277	. . 3 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐴 / 𝐶) = (𝐴 · (𝐶↑_𝑐-1)))
21	20	oveq2d 5891	. 2 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b (𝐴 / 𝐶)) = (𝐵 log_b (𝐴 · (𝐶↑_𝑐-1))))
22		simpll 527	. . . . 5 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → 𝐵 ∈ ℝ⁺)
23		simplr 528	. . . . 5 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → 𝐵 # 1)
24		simprr 531	. . . . 5 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → 𝐶 ∈ ℝ⁺)
25		rplogbcl 14367	. . . . 5 ⊢ ((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1 ∧ 𝐶 ∈ ℝ⁺) → (𝐵 log_b 𝐶) ∈ ℝ)
26	22, 23, 24, 25	syl3anc 1238	. . . 4 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b 𝐶) ∈ ℝ)
27		recn 7944	. . . 4 ⊢ ((𝐵 log_b 𝐶) ∈ ℝ → (𝐵 log_b 𝐶) ∈ ℂ)
28		mulm1 8357	. . . . 5 ⊢ ((𝐵 log_b 𝐶) ∈ ℂ → (-1 · (𝐵 log_b 𝐶)) = -(𝐵 log_b 𝐶))
29	28	oveq2d 5891	. . . 4 ⊢ ((𝐵 log_b 𝐶) ∈ ℂ → ((𝐵 log_b 𝐴) + (-1 · (𝐵 log_b 𝐶))) = ((𝐵 log_b 𝐴) + -(𝐵 log_b 𝐶)))
30	26, 27, 29	3syl 17	. . 3 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → ((𝐵 log_b 𝐴) + (-1 · (𝐵 log_b 𝐶))) = ((𝐵 log_b 𝐴) + -(𝐵 log_b 𝐶)))
31		simprl 529	. . . . . 6 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → 𝐴 ∈ ℝ⁺)
32		rplogbcl 14367	. . . . . 6 ⊢ ((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1 ∧ 𝐴 ∈ ℝ⁺) → (𝐵 log_b 𝐴) ∈ ℝ)
33	22, 23, 31, 32	syl3anc 1238	. . . . 5 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b 𝐴) ∈ ℝ)
34	33	recnd 7986	. . . 4 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b 𝐴) ∈ ℂ)
35	26	recnd 7986	. . . 4 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b 𝐶) ∈ ℂ)
36	34, 35	negsubd 8274	. . 3 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → ((𝐵 log_b 𝐴) + -(𝐵 log_b 𝐶)) = ((𝐵 log_b 𝐴) − (𝐵 log_b 𝐶)))
37	30, 36	eqtr2d 2211	. 2 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → ((𝐵 log_b 𝐴) − (𝐵 log_b 𝐶)) = ((𝐵 log_b 𝐴) + (-1 · (𝐵 log_b 𝐶))))
38	3, 21, 37	3eqtr4d 2220	1 ⊢ (((𝐵 ∈ ℝ⁺ ∧ 𝐵 # 1) ∧ (𝐴 ∈ ℝ⁺ ∧ 𝐶 ∈ ℝ⁺)) → (𝐵 log_b (𝐴 / 𝐶)) = ((𝐵 log_b 𝐴) − (𝐵 log_b 𝐶)))

Colors of variables: wff set class

Syntax hints: → wi 4 ∧ wa 104 = wceq 1353 ∈ wcel 2148 class class class wbr 4004 (class class class)co 5875 ℂcc 7809 ℝcr 7810 0cc0 7811 1c1 7812 + caddc 7814 · cmul 7816 − cmin 8128 -cneg 8129 # cap 8538 / cdiv 8629 ℝ⁺crp 9653 ↑_𝑐ccxp 14281 log_b clogb 14364

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 614 ax-in2 615 ax-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-13 2150 ax-14 2151 ax-ext 2159 ax-coll 4119 ax-sep 4122 ax-nul 4130 ax-pow 4175 ax-pr 4210 ax-un 4434 ax-setind 4537 ax-iinf 4588 ax-cnex 7902 ax-resscn 7903 ax-1cn 7904 ax-1re 7905 ax-icn 7906 ax-addcl 7907 ax-addrcl 7908 ax-mulcl 7909 ax-mulrcl 7910 ax-addcom 7911 ax-mulcom 7912 ax-addass 7913 ax-mulass 7914 ax-distr 7915 ax-i2m1 7916 ax-0lt1 7917 ax-1rid 7918 ax-0id 7919 ax-rnegex 7920 ax-precex 7921 ax-cnre 7922 ax-pre-ltirr 7923 ax-pre-ltwlin 7924 ax-pre-lttrn 7925 ax-pre-apti 7926 ax-pre-ltadd 7927 ax-pre-mulgt0 7928 ax-pre-mulext 7929 ax-arch 7930 ax-caucvg 7931 ax-pre-suploc 7932 ax-addf 7933 ax-mulf 7934

This theorem depends on definitions: df-bi 117 df-stab 831 df-dc 835 df-3or 979 df-3an 980 df-tru 1356 df-fal 1359 df-nf 1461 df-sb 1763 df-eu 2029 df-mo 2030 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ne 2348 df-nel 2443 df-ral 2460 df-rex 2461 df-reu 2462 df-rmo 2463 df-rab 2464 df-v 2740 df-sbc 2964 df-csb 3059 df-dif 3132 df-un 3134 df-in 3136 df-ss 3143 df-nul 3424 df-if 3536 df-pw 3578 df-sn 3599 df-pr 3600 df-op 3602 df-uni 3811 df-int 3846 df-iun 3889 df-disj 3982 df-br 4005 df-opab 4066 df-mpt 4067 df-tr 4103 df-id 4294 df-po 4297 df-iso 4298 df-iord 4367 df-on 4369 df-ilim 4370 df-suc 4372 df-iom 4591 df-xp 4633 df-rel 4634 df-cnv 4635 df-co 4636 df-dm 4637 df-rn 4638 df-res 4639 df-ima 4640 df-iota 5179 df-fun 5219 df-fn 5220 df-f 5221 df-f1 5222 df-fo 5223 df-f1o 5224 df-fv 5225 df-isom 5226 df-riota 5831 df-ov 5878 df-oprab 5879 df-mpo 5880 df-of 6083 df-1st 6141 df-2nd 6142 df-recs 6306 df-irdg 6371 df-frec 6392 df-1o 6417 df-oadd 6421 df-er 6535 df-map 6650 df-pm 6651 df-en 6741 df-dom 6742 df-fin 6743 df-sup 6983 df-inf 6984 df-pnf 7994 df-mnf 7995 df-xr 7996 df-ltxr 7997 df-le 7998 df-sub 8130 df-neg 8131 df-reap 8532 df-ap 8539 df-div 8630 df-inn 8920 df-2 8978 df-3 8979 df-4 8980 df-n0 9177 df-z 9254 df-uz 9529 df-q 9620 df-rp 9654 df-xneg 9772 df-xadd 9773 df-ioo 9892 df-ico 9894 df-icc 9895 df-fz 10009 df-fzo 10143 df-seqfrec 10446 df-exp 10520 df-fac 10706 df-bc 10728 df-ihash 10756 df-shft 10824 df-cj 10851 df-re 10852 df-im 10853 df-rsqrt 11007 df-abs 11008 df-clim 11287 df-sumdc 11362 df-ef 11656 df-e 11657 df-rest 12690 df-topgen 12709 df-psmet 13450 df-xmet 13451 df-met 13452 df-bl 13453 df-mopn 13454 df-top 13501 df-topon 13514 df-bases 13546 df-ntr 13599 df-cn 13691 df-cnp 13692 df-tx 13756 df-cncf 14061 df-limced 14128 df-dvap 14129 df-relog 14282 df-rpcxp 14283 df-logb 14365

This theorem is referenced by: logbrec 14381

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