x2-2/2x+1小于等于1
(x²-2)/(2x+1) ≤ 1
(x²-2) ≤ (2x+1)
(x²-2) - (2x+1) ≤ 0
x²-2 - 2x - 1 ≤ 0
x² - 2x - 3 ≤ 0
(x+1)(x-3) ≤ 0
(x+1) ≥ 0,x≥-1,(x-3)≤ 0,x≤ 3.
3 ≥ x ≥ -1