JEE Main & Advanced Mathematics Differential Equations Question Bank Variable Separable type differential equations

  • question_answer
    The solution of the differential equation \[(1+{{x}^{2}})\frac{dy}{dx}=x(1+{{y}^{2}})\]is              [AISSE 1983]

    A)                 \[2{{\tan }^{-1}}y=\log (1+{{x}^{2}})+c\]

    B)                 \[{{\tan }^{-1}}y=\log (1+{{x}^{2}})+c\]

    C)                 \[2{{\tan }^{-1}}y+\log (1+{{x}^{2}})+c=0\]

    D)                 None of these

    Correct Answer: A

    Solution :

                       \[(1+{{x}^{2}})\frac{dy}{dx}=x(1+{{y}^{2}})\]Þ\[\frac{1}{1+{{y}^{2}}}dy=\frac{x}{1+{{x}^{2}}}dx\]         On integrating, we get \[{{\tan }^{-1}}y=\frac{1}{2}\log (1+{{x}^{2}})+c\]                                 Þ \[2{{\tan }^{-1}}y=\log (1+{{x}^{2}})+c\].


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