4.(x-1)(x-a)≥0 6.(x-1)²当a≥1时,x≤1或x≥a => x²-5x+8-x≤log2(1)
=>-x≤0
=> x≥0
x²-6x+8≤0
(x-2)(x-4)≤0
=> 2≤x≤4
C R(B)=x4
A∩C R(B)=0≤x4
4.(x-1)(x-a)≥0 6.(x-1)²当a≥1时,x≤1或x≥a => x²-5x+8-x≤log2(1)
=>-x≤0
=> x≥0
x²-6x+8≤0
(x-2)(x-4)≤0
=> 2≤x≤4
C R(B)=x4
A∩C R(B)=0≤x4