X^2+2XY+6X+2Y^2+4Y+10=0求X Y

(x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) 1-2/x+y=xy,4y+6x=xy.求xy的解? 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 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 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) .(x+y-2)(x+y-2xy)+(xy-1)^2 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 2X^+XY-Y^-4X+5Y-6 2x^+xy-y^-4x+5y-6=? x-y/x^2+xy除以xy-x^2/x^2y^2-x^4*1/x-y 计算:2xy/(x+y)².(x+y)/4y 化简:[4xy(x-y)^-1 + (xy^-1 - x^-1y)/(x^-1 + y^-1)] / (x+y)^2 x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) (-x-y)(x^2+xy+y^2)