2x-y)^2-(x-y)^2 =(2x-y+x-y)(2x-y-x+y) =3x(3x-2y)最后一步怎么理解
已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
1、x(x-y)(x+y)-x(x+y)^2
化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方
【x-3y][x+y]-[x-2y][x +2y]-[x-y
[(3x+y)(x-y)-(2x+3y)(x-y)]*(x-y)
有这样一道题:"计算(2*x*x*x-3*x*x*y-2*x*y*y)-(x*x*x-2*x*y*y+y*y*y)+【-
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20