JEE Main & Advanced Mathematics Sequence & Series Question Bank Logarithmic series

  • question_answer
    The sum of the series \[{{\log }_{4}}2-{{\log }_{8}}2+{{\log }_{16}}2....\] is    [MNR 1994; Roorkee 1994; MP PET 2000]

    A) \[{{e}^{2}}\]

    B) \[{{\log }_{e}}2\]

    C) \[{{\log }_{e}}3-2\]

    D) \[1-{{\log }_{e}}2\]

    Correct Answer: D

    Solution :

    Since \[{{\log }_{{{y}^{n}}}}{{x}^{m}}=\frac{m}{n}{{\log }_{y}}x\]and \[{{\log }_{x}}x=1\]. \[\therefore \,\,\,S=\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{5}+....\] Also \[{{\log }_{e}}(1+x)=x-\frac{{{x}^{2}}}{2}+\frac{{{x}^{3}}}{3}-\frac{{{x}^{4}}}{4}+....\] Putting \[x=1,S=1-{{\log }_{e}}2\].


You need to login to perform this action.
You will be redirected in 3 sec spinner