若f(x)满足2(log1/2 X)^2-14log4X+3

若f(x)满足2(log1/2 X)^2-14log4X+3

原式=2(log2 X)^2-7(log2 X)+3<=0
f(x)=[(log2 X)-1][(log2 X)-2]
令log2 X=t
2t^2-7t+3<=0
解得1/2<=t<=3
设h(t)=(t-1)(t-2)=t^2-3t+2
-1/4<=h(t)<=2

楼主已解