课后训练1.lg20+log10025的值为( )A.2B.-2C.D.2.计算2log525+3log264-8log71等于( )A.14B.220C.D.223.若lnx-lny=a,则等于( )[来源:www.shulihua.netwww.shulihua.net]A.B.aC.D.3a4.已知a=lgx,则a+3=( )A.lg(3x)B.lg(x+3)C.lgx3D.lg(1000x)5.设2a=5b=m,且,则m等于( )A.B.10C.20D.1006.化简:______.7.若,则x=______.8.若logax=2,logbx=3,logcx=6,则logabcx的值为__________.[来源:www.shulihua.netwww.shulihua.net]89.(1)计算(log63)2+log618·log62;(2)已知log23=a,log37=b,试用a,b表示log1456.10.已知x,y,z为正数,3x=4y=6z,2x=py.(1)求p;(2)证明:.
参考答案1答案:A2答案:D3答案:D4答案:D5答案:A6答案:-57答案:[来源:www.shulihua.net]8答案:19答案:解:(1)原式=(log63)2+(log63+1)log62=[来源:www.shulihua.net]=(log63)2+(1+log63)(1-log63)=(log63)2+1-(log63)2=1.(2)∵log23=a,∴.∴log27=ab.∴.[来源:www.shulihua.net]10答案:(1)解:设3x=4y=6z=k(显然k>0,且k≠1),则x=log3k,y=log4k,z=log6k.由2x=py得2log3k=plog4k=.∵log3k≠0,∴p=2log34.(2)证明:=.