J & K CET Engineering J and K - CET Engineering Solved Paper-2010

  • question_answer
    The order and degree of the differential equation  \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+y+{{\left( \frac{dy}{dx}+\frac{{{d}^{3}}y}{d{{x}^{3}}} \right)}^{5/2}}=0\] are respectively

    A)  \[3,\,\,\,2\]           

    B)  \[2,\,\,3\]

    C)  \[3,\,\,1\]

    D)  \[3,\,\,5\]

    Correct Answer: D

    Solution :

    Given,   differential equation is \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+y+{{\left( \frac{dy}{dx}+\frac{{{d}^{3}}y}{d{{x}^{3}}} \right)}^{5/2}}=0\] \[\Rightarrow \] \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+y=-{{\left( \frac{dy}{dx}+\frac{{{d}^{3}}y}{d{{x}^{3}}} \right)}^{5/2}}\] On squaring both sides, we get \[{{\left( \frac{{{d}^{2}}y}{d{{x}^{2}}}+y \right)}^{2}}+{{\left( \frac{dy}{dx}+\frac{{{d}^{3}}y}{d{{x}^{3}}} \right)}^{5}}\] Clearly, order and degree of this differential equation are 3 and 5 respectively.


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