5x*2y=（x-y）^2 x+9y=55 求x、y

4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 分式的加减:[(x/y-y/x)除以（x+y）+x（1/y-1/x)]除以1+x/y,其中x=5,y=2 5x*2y=（x-y）^2 x+9y=55 求x、y 先化简,再求值 [2/3x - 2/x+y（x+y/3x -x-y）]*x/x-y,其中5x+3y=0 2(x-y)=5y,x-y=-5 x-y / 5y= (y-x)^2 / ( ) 5x=3y,(2x+y)的平方=5x(x+y)+9 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 x*x+2x+y*y-4y+5=0 x= y= 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, (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5)