The solution of the differential equation $\log_e \left(\frac{dy}{dx}\right)=5x+2y$ is given by
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $2e^{5x}+5e^{-2y}+C=0$: C is an arbitrary constant
Given: $\log_e\left(\frac{dy}{dx}\right) = 5x + 2y$
Take exponential both sides:
$\frac{dy}{dx} = e^{5x + 2y} = e^{5x} \cdot e^{2y}$
Separate variables:
$\frac{dy}{e^{2y}} = e^{5x} dx$
Integrate both sides:
$\int e^{-2y} dy = \int e^{5x} dx$
Left side: $\int e^{-2y} dy = \frac{-1}{2} e^{-2y}$
Right side: $\int e^{5x} dx = \frac{1}{5} e^{5x}$
So:
$\frac{-1}{2} e^{-2y} = \frac{1}{5} e^{5x} + C$
Multiply both sides by 10:
$-5e^{-2y} = 2e^{5x} + 10C$
Bring all terms to one side:
$2e^{5x} + 5e^{-2y} + C = 0$ (absorbing $10C$ into arbitrary constant $C$)