(x^2－4y^2)/(x^2＋2xy＋y^2)÷(x＋2y)/(x^2＋xy)÷(x^2－2xy)/(x+y)
＝{(x＋2y)(x－2y)}/(x＋y)^2÷(x＋2y)/x(x＋y)÷x(x－2y)/(x+y)
＝1
原式＝2(x－3)/(x－2)^2÷(x－3)/(x－2)＝2/(x－2),当x＝－1时,原式＝2/(－1－2)＝－2／3
原式＝（x-y)(x+y)/xy×1/(x-y)×(x+y)^2＝1/xy(x+y)＝1/(x^2y+xy^2)
原式＝{(x-2)(x-3)}/{(x+1)(x-1)} × x(x+1)/(x-3) × 3(x-1)/(x-2)=3x