3X+5Y=40 4X+3Y=46 Y=?X=?

（5x+3y)(3y-5x)-(4x-y)(4y+x)= 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 (x+y)(x+2y)(x+3y)(x+4y)=-40 3X+5Y=40 4X+3Y=46 Y=?X=? 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 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)+...-( 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 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 (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20