2.4   ODE No. 4

\[ -e^{-x^2} x+y'(x)+2 x y(x)=0 \] Mathematica : cpu = 0.0389584 (sec), leaf count = 30


\[\left \{\left \{y(x)\to \frac {1}{2} e^{-x^2} x^2+c_1 e^{-x^2}\right \}\right \}\] Maple : cpu = 0.007 (sec), leaf count = 18


\[y \relax (x ) = \left (\frac {x^{2}}{2}+c_{1}\right ) {\mathrm e}^{-x^{2}}\]

Hand solution

\begin {equation} \frac {dy}{dx}+2xy\relax (x) =e^{-x^{2}}x \tag {1} \end {equation}

Integrating factor \(\mu =e^{\int 2xdx}=e^{x^{2}}\). Hence (1) becomes

\begin {align*} \frac {d}{dx}\left (e^{x^{2}}y\relax (x) \right ) & =e^{x^{2}}e^{-x^{2}}x\\ \frac {d}{dx}\left (e^{x^{2}}y\relax (x) \right ) & =x \end {align*}

Integrating both sides

\begin {align*} e^{x^{2}}y\relax (x) & =\frac {x^{2}}{2}+C\\ y\relax (x) & =e^{-x^{2}}\left (\frac {x^{2}}{2}+C\right ) \end {align*}