Differential Equations Question 40

Question: The general solution of the differential equation $ e^{y}\frac{dy}{dx}+(e^{y}+1)\cot x=0 $ is

Options:

A) $ (e^{y}+1)\cos x=K $

B) $ (e^{y}+1)cosecx=K $

C) $ (e^{y}+1)\sin x=K $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ \frac{dy}{dx}+\frac{(e^{y}+1)\cot x}{e^{y}}=0 $

Therefore $ \int _{{}}^{{}}{\frac{e^{y}}{e^{y}+1}}dy+\int _{{}}^{{}}{\cot xdx}=0 $

Therefore $ \log (e^{y}+1)+\log \sin x=\log K $

Therefore $ (e^{y}+1)\sin x=K $ .