用对数换底公式，如log3(5)与log4(5)解：log3(5)=1/log5(3)>0log4(5)=1/log5(4)>0log3(5)/log4(5)=log5(4)/log5(3)=log3(4)>1因为log4(5)>0,所以，log3(5)>log4(5)注；如果两个真数均为1的话，则两数都是零，即两数相等