CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2004

  • question_answer
    If\[y=lo{{g}_{a}}x+lo{{g}_{x}}a+lo{{g}_{x}}x+lo{{g}_{a}}a,\]then\[\frac{dy}{dx}\]is equal to:

    A)  \[\frac{1}{x}+x\log a\]                 

    B)  \[\frac{\log a}{x}+\frac{x}{\log a}\]

    C)         \[\frac{1}{x\log a}+x\log a\]

    D)         \[\frac{1}{x\log a}-\frac{\log a}{x{{(\log x)}^{2}}}\]

    E)  none of these

    Correct Answer: D

    Solution :

    \[y={{\log }_{a}}+\frac{\log a}{\log x}+1+1\] On differentiating, we get \[\frac{dy}{dx}=\frac{1}{x}{{\log }_{a}}e-\log a{{\left( \frac{1}{\log x} \right)}^{2}}.\frac{1}{x}\] \[=\frac{1}{x\log a}-\frac{\log a}{x{{(\log x)}^{2}}}\]       


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