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

  • question_answer
    \[1+\frac{{{4}^{2}}}{3\,!}+\frac{{{4}^{4}}}{5\,!}+......\infty =\]

    A) \[\frac{{{e}^{4}}+{{e}^{-4}}}{4}\]

    B) \[\frac{{{e}^{4}}-{{e}^{-4}}}{4}\]

    C) \[\frac{{{e}^{4}}+{{e}^{-4}}}{8}\]

    D) \[\frac{{{e}^{4}}-{{e}^{-4}}}{8}\]

    Correct Answer: D

    Solution :

    \[S=1+\frac{{{4}^{2}}}{3\ !}+\frac{{{4}^{4}}}{5\ !}+........\infty \] \[=\frac{1}{4}\left\{ 4+\frac{{{4}^{3}}}{3\ !}+\frac{{{4}^{5}}}{5\,!}+...... \right\}=\frac{1}{4}\left( \frac{{{e}^{4}}-{{e}^{-4}}}{2} \right)\].


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