计算3x/(x-3y)+(x+y)/(4y-x)-7y/(x-4y)=?

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) 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 (x-3y)(y+2x)-(4y-3x)(3x+4y)计算 计算（2x-3y)(x+4y)-(3x+y)(x-2y) 计算【3(x-y)^2(x+y)^-2/4(x+y)^2(x-y)^-2】^-2 x-4y分之3x + 4y-x分之x+y - x*x-4y分之7y 计算:[(2x - 3y)^2 - (x-y)(4x+2y)] / 2y 计算(x+y)(x+y)^2(-x-y)^3 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 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 有这样一道题:"计算(2*x*x*x-3*x*x*y-2*x*y*y)-(x*x*x-2*x*y*y+y*y*y)+【- 计算:(-x-2y) * (3x-y)