化简：[(-3x^2y^4)^2·x^3-2x·(3x^2y^2)^3·1/2y^2]÷9x^7y^8

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：2x-{-3y+[4x-(3x-y]} 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 1/(x-y)+1/(x+y)+2x/(x^2+y^2)+4x^3/(x^4+y^4)化简 化简:5(x-y)+2(x+y)-3(x-y) 化简3(x-y)-7(x--y)+2(y-x) 化简-(-3x-y+2z)-{-x+【4x-(x-y-z)-3x+2z} 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 化简(X-2Y)-(Y-3X) 化简：(4x-3y)-[-(2x+y)+(x-y)]-5x 化简 3x(x^2-x-1)-(x+1)(3x^-x) X^3(x-y)+x(y-x) x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² (x+3y-4)(2x-y) 计算（2x-3y)(x+4y)-(3x+y)(x-2y)（2x-3y)(x+4y)-(3x+y)(x-2y) 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) (x+y)-(x-y)^3÷(x-y)(x+y)×2y化简e ,