JEE Main & Advanced Mathematics Differential Equations Question Bank Formation of differential equations

  • question_answer
    The differential equation for which \[{{\sin }^{-1}}x+{{\sin }^{-1}}y=c\] is given by          [Karnataka CET 2003]

    A)                 \[\sqrt{1-{{x}^{2}}}\,\,dx\,\,+\sqrt{1-{{y}^{2}}}\,\,dy=0\]

    B)                 \[\sqrt{1-{{x}^{2}}}\,\,dy\,\,+\sqrt{1-{{y}^{2}}}\,\,dx=0\]

    C)                 \[\sqrt{1-{{x}^{2}}}\,\,dy\,\,-\sqrt{1-{{y}^{2}}}\,\,dx=0\]

    D)                 \[\sqrt{1-{{x}^{2}}}\,\,dx\,-\sqrt{1-{{y}^{2}}}\,\,dy=0\]

    Correct Answer: B

    Solution :

                       Given equation is \[{{\sin }^{-1}}x+{{\sin }^{-1}}y=c\]               .....(i)         On differentiating w.r.t. to x, we get         \[\frac{1}{\sqrt{1-{{x}^{2}}}}+\frac{1}{\sqrt{1-{{y}^{2}}}}\frac{dy}{dx}=0\]Þ\[\frac{dy}{dx}=-\frac{\sqrt{1-{{y}^{2}}}}{\sqrt{1-{{x}^{2}}}}\]                 Þ \[\sqrt{1-{{x}^{2}}}\,\,dy+\sqrt{1-{{y}^{2}}}\,\,dx=0\].


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