问题描述: 已知x满足不等式?log1/2 x +3≤0求函数f(x)=(log2 x/4)(log2 x/2)的最值 1个回答 分类:数学 2014-09-28 问题解答: 我来补答 log1/2 x +3≤0有log1/2 x ≤-3=log1/2 8∵log1/2(x)是减函数,有∴ X≥8.令t=log(2) x ( t≥3)此时函数f(x)等价于:y=(log2 x/4)(log2 x/2)=(log2 x-log2 4)(log2 x-log2 2) =(log2 x-2)(log2 x-1) =(t-2)(t-1)=t²-3t+2=[t-(3/2)]²-(1/4)其中,t≥3则是当t=3,即log(2) x =3,x=8时y取得最小值2,且f(x)无最大值 展开全文阅读