Problem 08 | Separation of Variables

Problem 08
$xy^2 \, dx + e^x \, dy = 0$,   when   $x \to \infty$,   $y \to \frac{1}{2}$.
 

Solution 08
$xy^2 \, dx + e^x \, dy = 0$

$\dfrac{xy^2 \, dx}{y^2 e^x} + \dfrac{e^x \, dy}{y^2 e^x} = 0$

$\dfrac{x \, dx}{e^x} + \dfrac{dy}{y^2} = 0$

$\displaystyle \int xe^{-x} \, dx + \int y^{-2} \, dy = 0$
 

For   $\displaystyle \int xe^{-x} \, dx$
Let
$u = x$,   $du = dx$

$dv = \int e^{-x} \, dx$,   $v = -e^{-x}$