2(x-3y)+(1/4x+5y)-3(1/4x-y)

（x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8 3x-2y=1 4x-5y 求解;一 (x-8y)(x-y) 二 (Y+2)(Y-2)-(Y-1)(Y+5) 三 (3X+4)(3X-4)-(2X+ 1) (2x+5y)(2x-5y)(-4x^2-25y^2) 2) [（x+y)(x-y)-(x-y)^2+2y(x-y 化简求值:(x+y)-(2x+1/2y)-(3x+1/6y)-(4x+1/12y)-(5x+1/20y)-.(10x+1 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 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 化简,并求值2(x-2y)²-4（x+3y)(x-3y)-2(x-y).(y+x)-5(-x-1)²