x+y=5000 x∕6000+y∕2000（求解!）二元一次方程！

x+y=5000 x∕6000+y∕2000（求解!）二元一次方程！ x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知(x-y)(y+x)=xy 求x∕y+y∕x=?求具体过程. 化简 x / y(x+y) - y / x(x+y) = x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 x+x+x+y=20 x+x+y=14 x=?y=? x+y=20,x-y=10,y= x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? y=x(x x+x+x+x+y+y+y=56 先化简,再求值：[(x-2y)²-(x+2y)(x-2y)∕(-4y),其中x=-1,y=2 已知x+y+y=20,x+y=15求x.y {(x,y) |x|+|y| x>y?x:y