y＝log2(x)＋logx(2x)的值域是?

设t=lgx,x>0,且x≠1,则t≠0,
y=t/lg2+(t+lg2)/t
=(t/lg2+lg2/t)+1,
|t/lg2+lg2/t|=|t|/lg2+lg2/|t|>=2,t=土lg2时取等号,
∴y的值域是(-∞,-1]∪[3,+∞）.