lgbn=λlgan, 于是
=
=
=
8*、[方法一](換底公式)
=
=……=
=λ,lgb1=λlga1,lgb2=λlga2,……,
log3645=
=
=
=
=![]()
=![]()
[方法三](直接換成以18為底得對(duì)數(shù))
,b=
=
,可以求得log32=
-2,log35=
,∴l(xiāng)og3645=
=
[方法二](36和45都有公共的質(zhì)因數(shù)3,換成以3為底的對(duì)數(shù)加以計(jì)算)a=
=
∴l(xiāng)og3645=
=
=![]()
![]()
![]()
由①②得lg2=
,lg3=
[方法一] (換成常用對(duì)數(shù))a=
=
① b=
=
②,
7、由已知log185=b,
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