4y^2-x^2/x^2÷x-2y/2x^2 2xy

（xy-x^2)乘以(xy)/(x-y) （x^2+xy/x-y)/（xy/x-y)计算 计算：(x+y/x-y)÷(xy+x^2) (x^2-xy)y÷y-x/xy怎么做? 因式分解：x×x-xy-2y×y-x-y x-y/x²÷x²-2xy+y²/xy*（xy-x²） (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) 计算:4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 作乘法:(x+y)(x^2-xy+y^2)；(x-y)(x^2+xy+y^2) x根号x+x根号y/xy-y^2)-（x+根号xy+y/x根号x-y根号）y