比较下列四个数的大小:0.2^-1,log1.2(0.3),log0.2(0.3),log0.2(0.5)

问题描述:

比较下列四个数的大小:0.2^-1,log1.2(0.3),log0.2(0.3),log0.2(0.5)

先比较log0.2(0.3),log0.2(0.5),因为0log1.2(0.3)而0.2^-1=(1/5)^-1=5,而使log0.2(x)=5的x=0.2^5log0.2(0.3)(log0.2(x)为减函数),所以0.2^-1>log0.2(0.3)综上所述,0.2^-1>log0.2(0.3)>log0.2(0.5)>log1.2(0.3)...