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问题: 对数函数的比较大小

比较大小
1.log20.8,log0.50.8
2.0.32,log0.20.3,20.3

解答:

(1)log(2,0.8)<log(2,1)=0,log(0.5,0.8)>log(0.5,1)=0
所以log(2,0.8)<log(0.5,0.8)
(2)因为0.3^2=0.09,
又因为0.2>0.3^2,所以√(0.2)>0.3,
log(0.2,0.3)>log(0.2,√(0.2))=0.5
log(0.2,0.3)<log(0.2,0.2)=1
即0.5<log(0.2,0.3)<1
且2^0.3>1
所以0.3^2< og(0.2,0.3)<2^0.3