CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    The integrating factor of the differential equation\[(y\log y)dx=(\log y-x)dy\]is

    A)  \[\frac{1}{\log y}\]                         

    B)  \[\log (\log y)\]

    C)  \[1+\log y\]      

    D)         \[\frac{1}{\log (\log y)}\]

    E)  \[\log y\]

    Correct Answer: E

    Solution :

    Given differential equation can be rewritten as \[\frac{dx}{dy}=\frac{(\log y-x)}{y\log y}\] \[\Rightarrow \]               \[\frac{dx}{dy}+\frac{x}{y\log y}=\frac{1}{y}\] \[\therefore \]  \[IF={{e}^{\int{\frac{1}{y\log y}}dy}}\]                 \[={{e}^{\log \log y}}=\log y\]   


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