JEE Main & Advanced AIEEE Solved Paper-2002

  • question_answer
    The value of \[{{2}^{1/4}}.\,{{4}^{1/8}}.\,\,{{8}^{1/16}}.....\,\,\infty \] is   AIEEE  Solved  Paper-2002

    A) 1  

    B)                                           2    

    C) 3/2                            

    D) 4

    Correct Answer: B

    Solution :

      The sum of infinite arithmetico geometric sequence is \[{{S}_{n}}=\frac{\alpha }{1-r}+\frac{dr}{{{(1-r)}^{2}}}\]. We have.  \[{{2}^{1/4}}.\,{{4}^{1/8}}{{.8}^{1/16}}...\]                    \[={{2}^{1/4}}{{.2}^{2/8}}{{.2}^{3/16}}....\]                    \[={{2}^{\frac{1}{4}\left[ 1+\frac{2}{3}+\frac{3}{{{2}^{2}}}+.... \right]}}\]                    \[={{2}^{\frac{1}{4}\left[ \frac{1}{1-\frac{1}{2}}+\frac{1\times \frac{1}{2}}{{{\left( 1-\frac{1}{2} \right)}^{2}}} \right]}}\]                    \[={{2}^{\frac{1}{4}[2+2]}}=2\]


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