The general solution of the differential equation $\frac{dy}{dx}e^{x-y}+x^2e^{-y}$ is equal to: |
$e^y=e^x+\frac{x^3}{3}+c$, where c is an arbitrary constant. $e^y=xe^x+\frac{x^3}{3}+c$, where c is an arbitrary constant. $e^y=2e^x+\frac{x^2}{4}+c$, where c is an arbitrary constant. $y=e^x+\frac{x^3}{3}+c$, where c is an arbitrary constant. |
$e^y=e^x+\frac{x^3}{3}+c$, where c is an arbitrary constant. |
The correct answer is Option (1) → $e^y=e^x+\frac{x^3}{3}+c$, where c is an arbitrary constant. $e^{x-y}\frac{dy}{dx}+x^{2}e^{-y}=0$ $\text{Multiply by }e^{y}:\quad e^{x}\frac{dy}{dx}+x^{2}=0$ $\frac{dy}{dx}=-x^{2}e^{-x}$ $\text{Let }u=e^{y}\;\Rightarrow\;\frac{du}{dx}=e^{y}\frac{dy}{dx}$ $e^{y}\frac{dy}{dx}=\frac{du}{dx}$ $\frac{du}{dx}=e^{y}\frac{dy}{dx}=e^{y}(-x^{2}e^{-x})=-x^{2}e^{y-x}$ $\text{But from }e^{x}\frac{dy}{dx}+x^{2}=0:\; e^{y}\frac{dy}{dx}=e^{y-x}(-x^{2})$ $\Rightarrow\; \frac{du}{dx}=e^{x}+x^{2}$ $\int du=\int (e^{x}+x^{2})dx$ $u=e^{x}+\frac{x^{3}}{3}+C$ $e^{y}=e^{x}+\frac{x^{3}}{3}+C$ The general solution is $e^{y}=e^{x}+\frac{x^{3}}{3}+C$ |