为什么：x^4+y^4-x^3y-xy^3=(x-y)(x^3-y^3),倒推我会,

因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 为什么：x^4+y^4-x^3y-xy^3=(x-y)(x^3-y^3),倒推我会, 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 化简2(x²y+xy)-3(x²y-xy)-4x²y 化简3（x²y+xy)-4(x²y-xy)-5x²y, （-3x^y+2xy)-( )=4x^+xy 分解因式 x(x-y)^5+xy(y-x)^4-x^3(x-y)3 x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 已知x+y=3,xy=-2,求(3x-4y+2xy)-(2x-5y+5xy)的值请说明为什么这么做 计算(3x-4y)-(3x+4y)-xy (4x-3y)(3x+4y)-xy 计算下面式子{x-y+[(4xy)/(x-y)]}{x-y-[(4xy)/(x-y)]} （x-y+4xy/x-y）(x+y-4xy/x-y) (x-y+4xy/x+y)(x+y-4xy/x+y)等于的多少? 谢谢! 化简计算:[x-y+4xy/(x-y)] * [x+y-4xy/(x+y)] 计算:[x-y+4xy/(x-y)] * [x+y-4xy/(x+y)]