若-3≤log(1/2)x≤-1/2,则函数y=(log(2)x-1)(log(2)x-2)的值域为?
问题描述:
若-3≤log(1/2)x≤-1/2,则函数y=(log(2)x-1)(log(2)x-2)的值域为?
答
由已知,1/2≤log(2)x≤3,y=[log(2)x]^2-3log(2)x+2=[log(2)x-3/2]^2-1/4
-1≤log(2)x-3/2≤3/2,所以0≤[log(2)x-3/2]^2≤9/4,所以
-1/4≤y=[log(2)x-3/2]^2-1/4≤2