化简：（x-3y）^2 -(x-3y)(x+3y)

化简：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 化简:5(x-y)+2(x+y)-3(x-y) 化简3(x-y)-7(x--y)+2(y-x) 2（x-y）²-3(x-y)(-y-x) (x+y)-(x-y)^3÷(x-y)(x+y)×2y化简e , 化简(X-2Y)-(Y-3X) x(x-y)2-(y-x)3 化简(x-3y)(3x+y)-(2x-3y)(2x-3y) (2x+3y)(3x-2y)-(x-2y)(x+2y)化简 [(x-2y)²+(x+y)(3x-y)-3y²]÷2x化简。 化简 [(x-y)^2(x+y)^-2/2(x+y)^2(x-y)^-2]^-3 化简：[(x+2y)^2-(x+y)(3x-y)-5y^2]/2x (2x+3y)(x-2y)-(y+2x)(2x-y) 化简 化简(2x+3y)(x-y)-(y+2x)(2x-y) 化简:(x-y)(x-2y)+(x+2y)(x-3y) 化简:2（3x-y）-3(x+7y)