令log2(x)=t
2[log0.5(x)]²-14log4(x)+3≤0
由对数换底公式 得：
2[-log2(x)]²-14[log(x/log2(4)]+3≤0
2t²-7t+3≤0
==>
1≤t≤3/2
f(x)=log2(x/2) log√2(√x/2)=[log2(x)-1]*{[log2(√x/2)]/log2(√2)]}
y=(t-1)[(1/2)t-1][1/2]
=(1/4)(t²-3t+2)
y(t)在【1,3/2】上单调减,
y(MAX)=0
y(min)= - 1/16