x+9y=234 9x+y=366
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
已知4x=9y求(1)x+y/y (2)y-x/2x
5x=3y,(2x+y)的平方=5x(x+y)+9
9y=3x-(x-1),4(x+y)-(2x+4)=8y
3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8
3y=2x y/3=x/2 12/x=9/y y/x=?y/x=?x/y=?
已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值.
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值
y=(x+4)(x+9)/x (x>0)
y-x=3 7x+5y=-9
X+Y=9 6X+7Y=59
3x-3y=9 x+y=5