1.{3（2x+5)-2y=37{7(x-2y)-4(3x+y)=212.{ 2x+1/3-3y+4/4=-1{ x-1/2-2y-3/3=-1/6

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 3x+5y-(x+y)=6 2(x+y)-3x=-7 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 1.解方程组{x+y=7,3x+y=172.{x+y=4,2x-y=53.{3x+2y=5x+2,2（3x+2y)=2x+8 x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²= 解方程组1.x+1/3=5x-y/5 7y=5x+25 (x=2,y=5) 2.2x-y/5=x+y/3=3(x=8,y=1) 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 化简:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) 已知7x+5y/2y-x=3/2,且x≠0,求X/x-4y 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 1.已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除4x 的值 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27