Solution of the differential equation $y \log_e y\, dx-x\, dy = 0$ is (Where c is an arbitrary constant) |
$|y|=|c\log_e(xy)|$ $|x| = |cy|$ $|x| = |c\log_e y|$ $|y| = |c\log_e x|$ |
$|y|=|c\log_e(xy)|$ |
The correct answer is Option (1) → $|y|=|c\log_e(xy)|$ ** Form the differential equation: $y\ln y\,dx - x\,dy = 0$ Separate variables: $\frac{dx}{x} = \frac{dy}{y\ln y}$ Integrate: $\displaystyle \int \frac{dx}{x} = \int \frac{dy}{y\ln y}$ $\ln|x| = \ln|\ln y| + C$ Rewrite: $\ln|x| - \ln|\ln y| = C$ $\ln \left|\frac{x}{\ln y}\right| = C$ Exponentiate: $\left|\frac{x}{\ln y}\right| = e^{C} = K$ $|x| = K |\ln y|$ or equivalently $|y| = |C \ln (xy)|$ |