化简1-x-y/x+2y÷x^2-y^2/x^2+4xy+4y^2

化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) 先化简,再求值(x-y/x+y)^2÷(y-x/x^2+2xy+y^2)^2*1/x+y,其中x=-4,y=1 x^2y+4xy+4y 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? (2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)+2x^4y^2÷(xy)^2 （1）x-y/x-2y÷x^2-y^2/x^2-4xy+4y^2 (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 计算:4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2 化简(x²y-4y²)/(x²+4xy+4y²)*[(4xy)/(x-2y)+x 1.化简：x²-4y²/x²+y²+2xy÷2y+x/x²+xy. 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 因式分解：x×x-xy-2y×y-x-y