-x^2-4y^2+4xy

(x^2+2xy+y^2-4xy)*(x^2-2xy+y^2+4xy) 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) 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2 （X-3xy+4xy-y）-[-2x-2（xy-3/2xy）-y]+6xy的过程 （-3x^y+2xy)-( )=4x^+xy (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2 3(x^2y+xy)-4(xy-2x^2y)-(-xy) 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) 当x-y=2xy时,求4x-3xy-4y/xy XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2) 3（x平方y+xy)-4(xy-2x平方y)-(xy) 1-2/x+y=xy,4y+6x=xy.求xy的解? 计算:2xy/(x+y)².(x+y)/4y 计算:4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2