The general solution of the differential equation $xdy +e^{-y}dx=xe^{x-y}dx$ is (given C is constant of integration) |
$e^x+log\, x -2xy =C$ $x^2+e^{-y}+xe^x=C$ $xe^y-ye^x+log \left(\frac{x}{y}\right)=C$ $e^y-e^x+log x=C$ |
$e^y-e^x+log x=C$ |
The correct answer is Option (4) → $e^y-e^x+log x=C$ $xdy +e^{-y}dx=xe^{x-y}dx$ $⇒xdy+\frac{dx}{e^{y}}=\frac{xe^xdx}{e^{y}}$ $⇒xdy=\frac{dx(xe^x-1)}{e^y}$ $⇒\int e^ydy=\int dx(e^x-\frac{1}{x})$ $⇒e^y=e^x-\log x+C$ $⇒e^y-e^x+\log x=C$ |