函数y=log2(x)+logx(2x)的值域是
y=log2(x)+logx(2x)=log2(x)+logx(2)+logx(x)=log2(x)+logx(2)+1
log2(x)与logx(2)互为倒数,故值域为(－∞,-1]∪[3,+∞)
-1]是怎么来的