化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=?

9y=3x-(x-1),4(x+y)-(2x+4)=8y 化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 {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 (x+3y-4)(2x-y) 1.（（y+2x)(-2x+y)+4(x+2y)^2)/3y 2.（2(x-y)^3-8(x-y）^2(x+y)+6y( （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 已知4x=9y求(1)x+y/y (2)y-x/2x 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20