化简:2（3x-y）-3(x+7y)

化简3(x-y)-7(x--y)+2(y-x) 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:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 化简:2（3x-y）-3(x+7y) 化简,亲快啊啊急!(3x-2y)(7x-y)-（4x+3y）（x-y） 化简:5(x-y)+2(x+y)-3(x-y) 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) -2x(3x-7y)+(x-y)(x^2+xy+y^2） 计算 （-7x^2-8y^2）*(-x^2+3y^2) (3x-2y)(y-3x)-(2x-y)(3x+y) 已知（x+y）2 =2,(x-y)3 =3,求(x+y)7(x-y)2(x+y)3(y-x)4 的值 已知方程组{(X+Y)-3(X-Y)=7,2(X+Y)+(X-Y）=-7}则(X+Y)(X-Y)= 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