JEE Main & Advanced Mathematics Differential Equations Question Bank Order and degree of differential equations

  • question_answer
    The degree of the differential equation \[\frac{{{d}^{2}}y}{d{{x}^{2}}}-\sqrt{\frac{dy}{dx}-3}=x\] is [Orissa JEE 2004]

    A)                 2

    B)                 1

    C)                 ½

    D)                 3

    Correct Answer: A

    Solution :

                       \[\frac{{{d}^{2}}y}{d{{x}^{2}}}-\sqrt{\frac{dy}{dx}-3}=x\Rightarrow \frac{{{d}^{2}}y}{d{{x}^{2}}}-x=\sqrt{\frac{dy}{dx}-3}\]            Squaring both sides, we get \[{{\left( \frac{{{d}^{2}}y}{d{{x}^{2}}}-x \right)}^{2}}=\left( \frac{dy}{dx}-3 \right)\]                 Þ\[{{\left( \frac{{{d}^{2}}y}{d{{x}^{2}}} \right)}^{2}}+{{x}^{2}}-2x\frac{{{d}^{2}}y}{d{{x}^{2}}}=\frac{dy}{dx}-3\]. Clearly, degree = 2.


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