General solution of the differential equation $\frac{dy}{dx}=e^{\frac{x^2}{2}}+xy$ is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → $y = (x+c)e^{\frac{x^2}{2}}$, where c is constant of integration.
$\frac{dy}{dx} = e^{\frac{x^{2}}{2}} + xy$
$\text{Linear DE: } \frac{dy}{dx} - xy = e^{\frac{x^{2}}{2}}$
$\text{Integrating factor: } IF = e^{\int -x\,dx} = e^{-\frac{x^{2}}{2}}$
$\text{Multiply both sides: } e^{-\frac{x^{2}}{2}}\frac{dy}{dx} - xe^{-\frac{x^{2}}{2}}y = 1$
$\text{LHS becomes } \frac{d}{dx}(ye^{-\frac{x^{2}}{2}})$
$\frac{d}{dx}(ye^{-\frac{x^{2}}{2}}) = 1$
$ye^{-\frac{x^{2}}{2}} = x + c$
$y = (x+c)e^{\frac{x^{2}}{2}}$