{(x-2y)^2-4y^2+2xy}÷2x

计算:4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2 (x^2-xy)y÷y-x/xy怎么做? 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) 计算:2xy/(x+y)².(x+y)/4y 计算（xy-y^2)÷x-y/xy (x^2+2xy+y^2-4xy)*(x^2-2xy+y^2+4xy) 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) (-x-y)(x^2+xy+y^2) (xy-x²)÷(x²-2xy+y²/xy)×（x-y/x²） x-y/x²÷x²-2xy+y²/xy*（xy-x²） 化简x^-y^/x^-2xy+y^ 2*(x-y)²(y-x)(xy) (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 ((xy+2)(xy-2)-2x²y²+5(xy-y)²)÷(2xy)