If y / x + X / y = 1, what is the derivative of Y

If y / x + X / y = 1, what is the derivative of Y

The equation is rewritten as
    y^2+x^2 = xy,
The differential on both sides of the equation is obtained
    2ydy+2xdx = ydx+xdy,
Put it in order
    dy/dx = …… ,
That is to say