作业帮llog2=a,log3=b 求log12--5
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运用换底log14(56)=log3(56)/log3(14)=log3(7*8)/log3(2*7)=〔log3(7)＋log3(8)〕/〔log3(7)＋log3(2)〕log3(2)=1/log
解a=log3'2,b=In2,c=5'1/21/a=log2'31/b=log2'e1/c=1/5'1/21/b>1/ca
答：ab=log2^7ab+1=log2^7+1=log2^14ab+3=log2^7+3=log2^56log14^56=(ab+3)/(ab+1)
lg12=2lg2+lg3=2a+blg12^5=(2a+b)5
log3[log3（log5a）]=0log3（log5a）=1log5a=3a=625log4[log4（log5b）]=0log4（log5b）=1log5b=4b=125所以a/b=625/12
7*(2/3)log2(3)=alog2(3)=3a/14log3(2)=14/(3a)log3(5)=blg2=log3(2)/log3(10)=log3(2)/[log3(2)+log3(5)]=
(log3(x)-3)*(1+log3(x))+m=0log^23(x)-2log3(x)-3+m=0设x1=ax2=b则log3(a)+log3(b)=2=log3(a*b)a*b=3^2=9再问：
点击图片就可以看清楚了,加油!
当lg2=a,lg3=b,log3^4=2(lg2)÷lg3=2a/bb分之2a
log9(9a+b)=log3√（ab),0.5log3(9a+b)=log3√（ab),log3√(9a+b)=log3√（ab),9a+b=ab,b=9a/(a-1),4a+b=4a+9a/(a-
a=lg10/lg3=1/lg3lg3=1/alg25/lg6=b2lg5/lg(2*3)=b2(1-lg2)/(lg2+lg3)=b所以2-2lg2=blg2+blg3lg2=(2-b/a)/(b+
由lg2=a,lg3=b得log2（3）=b/a,log3(2)=a/b,所以log3（4）=2log3（2）=2a/blog2(12)=log2(4X3)=2+log2(3)=2+b/a再问：不太懂
log4(log5a)=1log5a=4a=5^4=625同理,b=5^3所以a/b=5
log9^5=a,log3^7=bLOG(3,7)=2LOG(9,7)=B==>LOG(9,7)=B/2lOG(35,9)=1/LOG(9,35)=1/(LOG(9,7)+LOG(9,5))=1/(B
因为3^b=5所以b=log(3)5所以log3(根号30)=1/2log3(30)=1/2log3(2*5*3)=1/2[log(3)2+log(3)5+log3(3)]=1/2(a+b+1)
a=(lg3)/(lg8)b=(lg5)/(lg3)ab=lg8/lg5=(3lg2)/(lg5)=3(lg(10/5)/(lg5))=3(lg10-lg5)/lg5=3(1-lg5)/lg5所以lg
a=lg3/lg2lg3=alg2b=lg7/lg3lg7=blg3=ablg2log42(56)=lg56/lg42=lg(2^3*7)/lg(2*3*7)=(3lg2+lg7)/(lg2+lg3+
log3^4=lg4/lg3=2lg2/lg3=2a/
log3(4)=lg4/lg3=2lg2/lg3=2a/