The differential equation $\frac{dy}{dx} +\frac{y^2}{x^2} =\frac{y}{x}$ has the solution |
$x=y (log x + C)$ $y = x(log y +C)$ $x= (y +C) log x $ $y = (x+ C) log y$ |
$x=y (log x + C)$ |
The correct answer is option (1) : $x=y (log x + C)$ We have, $\frac{dy}{dx} +\frac{y^2}{x^2}=\frac{y}{x}$ Putting $y = vx $ and $\frac{dy}{dx} = v + x\frac{dv}{dx}, $ we get $v + x\frac{dv}{dx} + v^2 = v $ $⇒x\frac{dv}{dx} = -v^2$ $⇒-\frac{1}{v^2}dv=\frac{1}{x}dx$ On integrating, we get $\frac{1}{v}= log x + C $ $⇒x = y (log x + C)$ |