(X+Y)（X^2+XY+Y^2)+2007(X+Y)=0 这个怎么得到的

(-x-y)(x^2+xy+y^2) 化简x^-y^/x^-2xy+y^ 2*(x-y)²(y-x)(xy) （x^2+xy/x-y)/（xy/x-y)计算 x^2+xy+x=36,y^2+xy+y=20,求x+y. X-Y/2X+2Y XY/X+Y² 因式分解：x×x-xy-2y×y-x-y 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) (x-y)[(x+y)^2-xy]+(x-y)[(x-y)^2+xy] .(x+y-2)(x+y-2xy)+(xy-1)^2 (x^2-xy)y÷y-x/xy怎么做? 代数 x^-y^/ x^-(y-z)^ 除以 x^+2xy+y^/(x-y)^-z^ 乘 x^+xy-xz/x^-xy (x+y)/x /(x-(2xy-y^2)/x) 因式分解 x^2-xy/xy-y^2约分 已知:x-xy=40,xy-y=-20,求代数式x-y和x+y-2xy的值. x-xy=40,xy-y= -20,求代数式x-y和x+y-2xy算试 已知x-xy=20,xy-y=-10,则x-y=( ),x+y-2xy=( ). 已知x-xy＝20,xy-y＝-10,则x-y＝?x+y-2xy＝?