(1)8X+2=9X+10 (2)2-15Y=5Y+3

10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组） 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 9y=3x-(x-1),4(x+y)-(2x+4)=8y 3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x1:4x-3y=8;y=7-5x;2:2x-7y=8,3x-8y-10=0;3:4x-y=-1;4:5x-10y+15 x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=