［（x+3y）(x－3y)-(x-3y)²］÷6y

(3x-y)(3y+x)-(x-y)(x+y) -3（x-y）（x-y）+3(x-y) 2（x-y）²-3(x-y)(-y-x) 求函数f（x,y）=x×x×x－y×y×y+3×x×x+3×y×y－9x的极值 3（x-1)³y-（1-x）³z m(x-y)²-x+y x²(x+y)(y-x)-xy(x+y)(x-y) 因式分解 x(x-y)2-(y-x)3 （y-x)+x(x-y)^3-(y-x)^4 因式分解 y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 [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：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 计算 3x+4y/x-y+3y/y-x-4x/x-y 3x+4y/x-y +3y/y-x -4x/x-y [(3x+y)(x-y)-(2x+3y)(x-y)]*(x-y) x(4y-x)(x-3y)+y(3y-x)(x-4y)因式分解 计算：x+2y/x-y+2x/y-x-3y/x-y 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方