How to prove the divergence of the sequence $(n!)^{1/n}$ [duplicate]












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  • Analysis: Prove divergence of sequence $(n!)^{frac2n}$

    5 answers




How to prove that
$(n!)^{1/n}$ tends to infinity as $n$ tends to infinity ?










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marked as duplicate by José Carlos Santos, user416281, Michael Burr, Simply Beautiful Art, Crostul Jan 12 at 13:11


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.























    -1












    $begingroup$



    This question already has an answer here:




    • Analysis: Prove divergence of sequence $(n!)^{frac2n}$

      5 answers




    How to prove that
    $(n!)^{1/n}$ tends to infinity as $n$ tends to infinity ?










    share|cite|improve this question











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    marked as duplicate by José Carlos Santos, user416281, Michael Burr, Simply Beautiful Art, Crostul Jan 12 at 13:11


    This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.





















      -1












      -1








      -1


      1



      $begingroup$



      This question already has an answer here:




      • Analysis: Prove divergence of sequence $(n!)^{frac2n}$

        5 answers




      How to prove that
      $(n!)^{1/n}$ tends to infinity as $n$ tends to infinity ?










      share|cite|improve this question











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      This question already has an answer here:




      • Analysis: Prove divergence of sequence $(n!)^{frac2n}$

        5 answers




      How to prove that
      $(n!)^{1/n}$ tends to infinity as $n$ tends to infinity ?





      This question already has an answer here:




      • Analysis: Prove divergence of sequence $(n!)^{frac2n}$

        5 answers








      real-analysis sequences-and-series






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      edited Jan 12 at 12:36









      Mohamad Misto

      516214




      516214










      asked Jan 12 at 12:30









      Nilesh KhatriNilesh Khatri

      195




      195




      marked as duplicate by José Carlos Santos, user416281, Michael Burr, Simply Beautiful Art, Crostul Jan 12 at 13:11


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









      marked as duplicate by José Carlos Santos, user416281, Michael Burr, Simply Beautiful Art, Crostul Jan 12 at 13:11


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
























          2 Answers
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          Observe that
          $$
          n!>left(frac{n}{2}right)^{frac{n}{2}}.
          $$

          This observation follows from writing out $n!$ as $n(n-1)(n-2)dots2cdot 1$ and taking half of the factors, those of size at least $frac{n}{2}$.



          Therefore,
          $$
          (n!)^{frac{1}{n}}>left(left(frac{n}{2}right)^{frac{n}{2}}right)^{frac{1}{n}}=left(frac{n}{2}right)^{frac{1}{2}},
          $$

          which diverges.






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            1












            $begingroup$

            Let $k$ be any positive integer. $(n!)^{1/n} geq (k(k+1)cdots n)^{1/n} geq k^{(n-k+1)/n}$ for $n >k$. Can you see from this that $(n!)^{1/n} to infty$?.






            share|cite|improve this answer









            $endgroup$




















              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              3












              $begingroup$

              Observe that
              $$
              n!>left(frac{n}{2}right)^{frac{n}{2}}.
              $$

              This observation follows from writing out $n!$ as $n(n-1)(n-2)dots2cdot 1$ and taking half of the factors, those of size at least $frac{n}{2}$.



              Therefore,
              $$
              (n!)^{frac{1}{n}}>left(left(frac{n}{2}right)^{frac{n}{2}}right)^{frac{1}{n}}=left(frac{n}{2}right)^{frac{1}{2}},
              $$

              which diverges.






              share|cite|improve this answer









              $endgroup$


















                3












                $begingroup$

                Observe that
                $$
                n!>left(frac{n}{2}right)^{frac{n}{2}}.
                $$

                This observation follows from writing out $n!$ as $n(n-1)(n-2)dots2cdot 1$ and taking half of the factors, those of size at least $frac{n}{2}$.



                Therefore,
                $$
                (n!)^{frac{1}{n}}>left(left(frac{n}{2}right)^{frac{n}{2}}right)^{frac{1}{n}}=left(frac{n}{2}right)^{frac{1}{2}},
                $$

                which diverges.






                share|cite|improve this answer









                $endgroup$
















                  3












                  3








                  3





                  $begingroup$

                  Observe that
                  $$
                  n!>left(frac{n}{2}right)^{frac{n}{2}}.
                  $$

                  This observation follows from writing out $n!$ as $n(n-1)(n-2)dots2cdot 1$ and taking half of the factors, those of size at least $frac{n}{2}$.



                  Therefore,
                  $$
                  (n!)^{frac{1}{n}}>left(left(frac{n}{2}right)^{frac{n}{2}}right)^{frac{1}{n}}=left(frac{n}{2}right)^{frac{1}{2}},
                  $$

                  which diverges.






                  share|cite|improve this answer









                  $endgroup$



                  Observe that
                  $$
                  n!>left(frac{n}{2}right)^{frac{n}{2}}.
                  $$

                  This observation follows from writing out $n!$ as $n(n-1)(n-2)dots2cdot 1$ and taking half of the factors, those of size at least $frac{n}{2}$.



                  Therefore,
                  $$
                  (n!)^{frac{1}{n}}>left(left(frac{n}{2}right)^{frac{n}{2}}right)^{frac{1}{n}}=left(frac{n}{2}right)^{frac{1}{2}},
                  $$

                  which diverges.







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                  share|cite|improve this answer










                  answered Jan 12 at 12:36









                  Michael BurrMichael Burr

                  27k23262




                  27k23262























                      1












                      $begingroup$

                      Let $k$ be any positive integer. $(n!)^{1/n} geq (k(k+1)cdots n)^{1/n} geq k^{(n-k+1)/n}$ for $n >k$. Can you see from this that $(n!)^{1/n} to infty$?.






                      share|cite|improve this answer









                      $endgroup$


















                        1












                        $begingroup$

                        Let $k$ be any positive integer. $(n!)^{1/n} geq (k(k+1)cdots n)^{1/n} geq k^{(n-k+1)/n}$ for $n >k$. Can you see from this that $(n!)^{1/n} to infty$?.






                        share|cite|improve this answer









                        $endgroup$
















                          1












                          1








                          1





                          $begingroup$

                          Let $k$ be any positive integer. $(n!)^{1/n} geq (k(k+1)cdots n)^{1/n} geq k^{(n-k+1)/n}$ for $n >k$. Can you see from this that $(n!)^{1/n} to infty$?.






                          share|cite|improve this answer









                          $endgroup$



                          Let $k$ be any positive integer. $(n!)^{1/n} geq (k(k+1)cdots n)^{1/n} geq k^{(n-k+1)/n}$ for $n >k$. Can you see from this that $(n!)^{1/n} to infty$?.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Jan 12 at 12:35









                          Kavi Rama MurthyKavi Rama Murthy

                          66.9k53067




                          66.9k53067















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