[(3x-1/2y^2)+3y(x-y/12)]÷[(2x+y)^2-4y(x+1/4y)]

（x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 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 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 (x+3y-4)(2x-y) [(3x-1/2y^2)+3y(x-y/12)]÷[(2x+y)^2-4y(x+1/4y)] 化简求值：[(3x-1\2y)^2+3y(x-y\12)]÷[(2x+y)^2-4y(x+1\4y)] 1、x(x-y)(x+y)-x(x+y)^2 [(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 先化简,再求值：[(x+y)(x-y)-(x-y)^2+2y(x-3y)]/(-4y),其中x=1,y=-2