Differential-Equations Question 361
Question: The general solution of the differential equation $ ydx,+(1+x^{2}){{\tan }^{-1}}xdy=0, $ is
[MP PET 1995]
Options:
A) $ y{{\tan }^{-1}}x=c $
B) $ x{{\tan }^{-1}}y=c $
C) $ y+{{\tan }^{-1}}x=c $
D) $ x+{{\tan }^{-1}}y=c $
Show Answer
Answer:
Correct Answer: A
Solution:
$ ydx+(1+x^{2}){{\tan }^{-1}}xdy=0 $
Þ $ \int_{{}}^{{}}{\frac{dx}{(1+x^{2}){{\tan }^{-1}}x}}=-\int_{{}}^{{}}{\frac{dy}{y}} $
Þ $ \frac{1}{2^{x}}-\frac{1}{2^{y}}=\frac{c_1}{\log 2}=c $
Þ $ \log (y{{\tan }^{-1}}x)+\log c=0 $
Þ $ y{{\tan }^{-1}}x=c $ .
BETA
