Find the general solution of the differential equation: $\log \left( \frac{dy}{dx} \right) = ax + by.$
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\frac{e^{ax}}{a} + \frac{e^{-by}}{b} = C$ ##
Given differential equation is
$\log \left( \frac{dy}{dx} \right) = ax + by$
$\Rightarrow \frac{dy}{dx} = e^{ax + by}$
$\Rightarrow \frac{dy}{dx} = e^{ax} \cdot e^{by}$
$\Rightarrow \frac{dy}{e^{by}} = e^{ax} dx$
$\Rightarrow e^{-by} dy = e^{ax} dx$
On integrating both sides, we get
$\int e^{-by} dy = \int e^{ax} dx$
$\frac{e^{-by}}{-b} = \frac{e^{ax}}{a} + C$
$\Rightarrow \frac{e^{ax}}{a} + \frac{e^{-by}}{b} + C = 0$