已知5x+4y=6 2x+3y=1,则x+y=

已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 已知5x+4y=6 2x+3y=1,则x+y= 已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知4x=9y求(1)x+y/y (2)y-x/2x {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 已知x,y满足x²+y²-4x+6y+13=0则(3x+y)²-(3x+y)(3x-y)的 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7