Show that the differential equation $\left(1+e^{\frac{x}{y}}\right) dx+e^{\frac{x}{y}}\left(1-\frac{x}{y}\right) dy=0$ is a homogeneous equation and find its solution.

(N/A) Given equation: $\left(1+e^{\frac{x}{y}}\right) dx+e^{\frac{x}{y}}\left(1-\frac{x}{y}\right) dy=0$
$\Rightarrow \frac{dx}{dy} = \frac{-e^{\frac{x}{y}}\left(1-\frac{x}{y}\right)}{1+e^{\frac{x}{y}}} = F(x, y)$
Since $F(\lambda x, \lambda y) = \frac{-e^{\frac{\lambda x}{\lambda y}}\left(1-\frac{\lambda x}{\lambda y}\right)}{1+e^{\frac{\lambda x}{\lambda y}}} = F(x, y) = \lambda^0 F(x, y)$,the equation is homogeneous.
Let $x = vy$,then $\frac{dx}{dy} = v + y\frac{dv}{dy}$.
Substituting into the equation:
$v + y\frac{dv}{dy} = \frac{-e^v(1-v)}{1+e^v}$
$y\frac{dv}{dy} = \frac{-e^v + ve^v}{1+e^v} - v = \frac{-e^v + ve^v - v - ve^v}{1+e^v} = \frac{-(v+e^v)}{1+e^v}$
Separating variables:
$\frac{1+e^v}{v+e^v} dv = -\frac{dy}{y}$
Integrating both sides:
$\int \frac{1+e^v}{v+e^v} dv = -\int \frac{1}{y} dy$
$\log(v+e^v) = -\log y + \log C = \log\left(\frac{C}{y}\right)$
$v+e^v = \frac{C}{y}$
Substituting $v = \frac{x}{y}$:
$\frac{x}{y} + e^{\frac{x}{y}} = \frac{C}{y}$
$x + ye^{\frac{x}{y}} = C$