计算:[1/(x-y) - 1/(x+y) + 2y/(x^2 + y^2) - 4x^2 y/(x^4 + y^4)

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 1) (2x+5y)(2x-5y)(-4x^2-25y^2) 2) [（x+y)(x-y)-(x-y)^2+2y(x-y 1、x(x-y)(x+y)-x(x+y)^2 计算(x-2y)^2-4(2x+y)(y-2x)+4x(y-2) 计算【3(x-y)^2(x+y)^-2/4(x+y)^2(x-y)^-2】^-2 (x-3y)(y+2x)-(4y-3x)(3x+4y)计算 计算（2x-3y)(x+4y)-(3x+y)(x-2y) 1 4(x-y+1)+y(y-2x) 把4（x-y+1)+y(y-2x)因式分解 4(x-y+1)+y(y-2x) x^2-y^2/x+y-4x(x-y)+y^2/2x-y, （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3)