Differential Equations Question 32

Question: The solution of $ \frac{dy}{dx}+\frac{y}{3}=1 $ is

[EAMCET 2002]

Options:

A) $ y=3+c{e^{x/3}} $

B) $ y=3+c{e^{-x/3}} $

C) $ 3y=c+{e^{x/3}} $

D) $ 3y=c+{e^{-x/3}} $

Show Answer

Answer:

Correct Answer: B

Solution:

Given, $ \frac{dy}{dx}+\frac{y}{3}=1 $ ; I.F. = $ {e^{\int{\frac{1}{3}dx}}}={e^{x/3}} $

Hence, solution is $ y.{e^{x/3}}=\int{1.{e^{x/3}}dx+c} $

$ y.{e^{x/3}}=3{e^{x/3}}+c $ ; $ y=3+c{e^{-x/3}} $ .