x－2y=50x－30y=5

｛5x+2y=18,y=－x x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x－2y=50x－30y=5 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 3x(2x＋y)－2x(x-y),其中x＝1,y=1/5 (2x-3y)²-(－2x-3y)(－2x+3y)x+y=10,3x-2y=5过程 解下列方程组:x-2/3x-1=2y,2(x+y)-5x+y=－4 ｛x=2y ｛2x－y=3 2(x-y)=5y,x-y=-5 2Y：30%=3X：50%求X:Y x-y / 5y= (y-x)^2 / ( ) x*x+2x+y*y-4y+5=0 x= y= x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 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 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1