D|x-2| = 1,则x1 = 3,x2 = 1分别代入代数式：y = x^2 * (x-1)/(x+2) - 4/x^2 -2x + 1 / (1/x^2) -1,得：y1 = 9 * 2 / 5 - 4/9 -6 + 9 - 1 = 5 + 3/5 - 4/9y2 = 0 -4 -2 + 1 - 1 = -6