5x+3y=11.5 3x+5y=14.9

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-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 （5x+3y)(3y-5x)-(4x-y)(4y+x)= 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) |x|=3 |y|=5 |x-y|=|x|+|y| 求 X+Y和 X-Y 等于多少 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 5(x+y-2)=3-y