计算 3(2x-7y)(7y+2x)+(4x+5y)(-5y-4x)

计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8 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 先化简,后求值（x+5y)(x+4y)(x-y)(x+y),其中,x=-2又2/3,y=3/7,用公式计算 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 方程式计算5X-2=Y 4X+3=Y 求X.Y 计算:(x+y)^2×(-x-y)^3×[-3/4(x-y)^3]×5/6(y-x)^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：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 计算（2x-3y)(x+4y)-(3x+y)(x-2y) (3x-4y)(5x-4y)-(7x-8y)(6y-5x)