｛5x+2y=18,

｛5x+2y=18,y=－x 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 解方程组：2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解方程组:2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 (计算方程组x+y)/2=6-(x-y)/3,6(x+y)-5(x-y)=18 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 计算题!【x+y+z=26；x-y=1；2x-y+z=18】!【x/3+y/5；x/2-2y/5=1】 2(x-y)=5y,x-y=-5 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 x-y / 5y= (y-x)^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 x*x+2x+y*y-4y+5=0 x= y= 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 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 求(X+Y)(X-Y)(X²+Y²),X=5 Y=2,