[4/（x^2-y^2)+（x+y)/(xy^2-x^2y)] / (x^2+xy-2y^2)/(x^2y+2xy^2)

（xy-x^2)乘以(xy)/(x-y) （x^2+xy/x-y)/（xy/x-y)计算 x^2y+4xy+4y 因式分解：x×x-xy-2y×y-x-y (x+y-2xy)(x+y-2)+(1-xy)² (x^2-xy)y÷y-x/xy怎么做? 作乘法:(x+y)(x^2-xy+y^2)；(x-y)(x^2+xy+y^2) (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y) (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 因式分解xy+y平方+x-y-2 x-y/xy-y^2计算 x根号x+x根号y/xy-y^2)-（x+根号xy+y/x根号x-y根号）y