Railways Quantitative Aptitude Power, Surds And Indices Sample Paper Surds Indices Sample Test Paper-4

  • question_answer
    \[\frac{{{(243)}^{\frac{n}{5}}}\times {{3}^{2n+1}}}{{{9}^{n}}\times {{3}^{n-1}}}=?\]

    A)  1                    

    B)  3        

    C)  9                    

    D)  \[{{3}^{n}}\]

    Correct Answer: C

    Solution :

    [c] \[\frac{{{(243)}^{\frac{n}{5}}}\times {{3}^{2n+1}}}{{{9}^{n}}\times {{3}^{n-1}}}=\frac{{{\left[ {{(3)}^{5}} \right]}^{\frac{n}{5}}}\times {{3}^{2n+1}}}{{{({{3}^{2}})}^{n}}\times {{3}^{n-1}}}\] \[=\frac{{{3}^{n}}\times {{3}^{2n+1}}}{{{3}^{2n}}\times {{3}^{n-1}}}\left[ {{a}^{m}}\times {{a}^{n}}={{a}^{m+n}} \right]\] \[=\frac{{{3}^{3n+1}}}{{{3}^{3n-1}}}\,\,\,\,\,\,\,\left[ \frac{{{a}^{n}}}{{{a}^{m}}}={{a}^{n-m}} \right]\] \[={{3}^{2}}=9\]


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