一道数学题log2=a，log3=b。那么log4/15等于？解答：是lg2=a,lg3=b吧lg(4/15)=lg(8/

解答：
是lg2=a,lg3=b吧
lg(4/15)
=lg(8/30)
=lg8-lg30
=lg2³-lg(3*10)
=3lg2-lg-lg10
=3a-b-1

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log4/15=log4-log15=2*log2-log[10*(3/2)]=2*log2-log10-log3/2=2*log2-log10-log3+log2=3*log2-log3-log10=3a-b+1

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3a-b+1

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