专题讲练2指、对、幂的大小比较

1.D[解析]作出函数y=log0.2x,y=log0.3x,y=log0.4x的图象如图所示,由图可得abc.故选D.

2.D[解析]0.20.50.20.2=0.040.10.20=1,即ab1,又c=log0.50.2log0.50.5=1,所以cba.故选D.

3.D[解析]因为0.800.84.20.74.20,所以1mp0,因为n=log0.74.2log0.71=0,所以n0,故npm.故选D.

4.D[解析]若a0b,则1a1b,故A错误;因为ab,所以a-b0,所以ln(a-b)∈R,故B错误;若0ab,则a2b2,故C错误