JEE Main & Advanced Mathematics Differential Equations Question Bank Linear defferential equations

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

    A)                 \[4xy={{x}^{4}}+c\]       

    B)                 \[xy={{x}^{4}}+c\]

    C)                 \[\frac{1}{4}xy={{x}^{4}}+c\]      

    D)                 \[xy=4{{x}^{4}}+c\]

    Correct Answer: A

    Solution :

                       The given equation \[\frac{dy}{dx}+\frac{y}{x}={{x}^{2}}\]is of the form                    \[\frac{dy}{dx}+Py=Q\]. So, I.F.= \[{{e}^{\int_{{}}^{{}}{\frac{1}{x}dx}}}={{e}^{\log x}}=x\]                    Hence required solution \[xy=\int_{{}}^{{}}{x.{{x}^{2}}dx+c}\]                                 Þ \[xy=\frac{{{x}^{4}}}{4}+c\] Þ \[4xy={{x}^{4}}+c\].


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