x/(3^3+4^3)+y/(3^3+6^3)=1 x/(5^3+4^3)+y/(5^3+6^3)=1 求证x+y=43

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 3x+2y/4=2x+y/5=x-y+1/6 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 （5x+3y)(3y-5x)-(4x-y)(4y+x)= x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5