Manipal Engineering Manipal Engineering Solved Paper-2011

  • question_answer
    Integrating factor of equation\[({{x}^{2}}+1)\frac{dy}{dx}+2xy={{x}^{2}}-1\]is

    A) \[\frac{2x}{{{x}^{2}}+1}\]                            

    B) \[\frac{{{x}^{2}}-1}{{{x}^{2}}+1}\]

    C) \[{{x}^{2}}+1\]                 

    D)  None of these

    Correct Answer: C

    Solution :

    Given differential equation can be rewritten as                 \[\frac{dy}{dx}+\frac{2x}{1+{{x}^{2}}}y=\frac{{{x}^{2}}-1}{{{x}^{2}}+1}\] Here,     \[P=\frac{2x}{1+{{x}^{2}}}\]and\[Q=\frac{{{x}^{2}}-1}{{{x}^{2}}+1}\] \[\therefore \]  \[IF=\int{{{e}^{\frac{2x}{1+{{x}^{2}}}dx}}}={{e}^{\log (1+{{x}^{2}})}}\]                 \[=1+{{x}^{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner