Limit with three square roots

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I have a task for school to calculate this limit at infinity, I have tried three times but i failed everytime.




$$lim_nrightarrowinftyleft(sqrt4n+1-sqrtn-sqrtn+1right)$$




I know what to do when there are two square roots but when there's three I don't know how to proceed can anyone help me ? Thanks










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  • Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
    – MRobinson
    1 hour ago














up vote
3
down vote

favorite












I have a task for school to calculate this limit at infinity, I have tried three times but i failed everytime.




$$lim_nrightarrowinftyleft(sqrt4n+1-sqrtn-sqrtn+1right)$$




I know what to do when there are two square roots but when there's three I don't know how to proceed can anyone help me ? Thanks










share|cite|improve this question









New contributor




Katarína Paľová is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
    – MRobinson
    1 hour ago












up vote
3
down vote

favorite









up vote
3
down vote

favorite











I have a task for school to calculate this limit at infinity, I have tried three times but i failed everytime.




$$lim_nrightarrowinftyleft(sqrt4n+1-sqrtn-sqrtn+1right)$$




I know what to do when there are two square roots but when there's three I don't know how to proceed can anyone help me ? Thanks










share|cite|improve this question









New contributor




Katarína Paľová is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I have a task for school to calculate this limit at infinity, I have tried three times but i failed everytime.




$$lim_nrightarrowinftyleft(sqrt4n+1-sqrtn-sqrtn+1right)$$




I know what to do when there are two square roots but when there's three I don't know how to proceed can anyone help me ? Thanks







limits






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edited 2 hours ago









cansomeonehelpmeout

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asked 2 hours ago









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  • Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
    – MRobinson
    1 hour ago
















  • Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
    – MRobinson
    1 hour ago















Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
– MRobinson
1 hour ago




Can you add your working out/thinking to the question? Try and extend your knowledge with 2 to what could happen with 3. You are adding them so the behavior is very similar.
– MRobinson
1 hour ago










4 Answers
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Hint: Since you know what to do when there are only two square roots, use the fact that$$(forall ninmathbbN):sqrt4n+1-sqrt n-sqrtn+1=left(sqrtn+frac14-sqrt nright)+left(sqrtn+frac14-sqrtn+1right).$$






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    up vote
    1
    down vote













    Set $1/n=h^2$



    $$lim_hto0^+dfracsqrt4+h^2-1-sqrt1+h^2h$$



    $$=lim_...dfracsqrt4+h^2-2h-lim_...dfracsqrt1+h^2-1h=0-0$$ on rationalization of the numerators






    share|cite|improve this answer



























      up vote
      0
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      Write $$frac((sqrt4n+1-sqrtn+1)-sqrtn)((sqrt4n+1-sqrtn+1)+sqrtn)sqrt4n+1-sqrtn+1+sqrtn$$






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        up vote
        0
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        $sqrt4n+1-(sqrtn+sqrtn+1)<sqrt4n+1-2sqrtn=sqrt4n+1-sqrt4n
        <frac1sqrt4n+1+sqrt4nto0$



        So, the original limit is $0$.






        share|cite|improve this answer








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          4 Answers
          4






          active

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          4 Answers
          4






          active

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          active

          oldest

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          up vote
          4
          down vote













          Hint: Since you know what to do when there are only two square roots, use the fact that$$(forall ninmathbbN):sqrt4n+1-sqrt n-sqrtn+1=left(sqrtn+frac14-sqrt nright)+left(sqrtn+frac14-sqrtn+1right).$$






          share|cite|improve this answer
























            up vote
            4
            down vote













            Hint: Since you know what to do when there are only two square roots, use the fact that$$(forall ninmathbbN):sqrt4n+1-sqrt n-sqrtn+1=left(sqrtn+frac14-sqrt nright)+left(sqrtn+frac14-sqrtn+1right).$$






            share|cite|improve this answer






















              up vote
              4
              down vote










              up vote
              4
              down vote









              Hint: Since you know what to do when there are only two square roots, use the fact that$$(forall ninmathbbN):sqrt4n+1-sqrt n-sqrtn+1=left(sqrtn+frac14-sqrt nright)+left(sqrtn+frac14-sqrtn+1right).$$






              share|cite|improve this answer












              Hint: Since you know what to do when there are only two square roots, use the fact that$$(forall ninmathbbN):sqrt4n+1-sqrt n-sqrtn+1=left(sqrtn+frac14-sqrt nright)+left(sqrtn+frac14-sqrtn+1right).$$







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered 2 hours ago









              José Carlos Santos

              128k17102190




              128k17102190




















                  up vote
                  1
                  down vote













                  Set $1/n=h^2$



                  $$lim_hto0^+dfracsqrt4+h^2-1-sqrt1+h^2h$$



                  $$=lim_...dfracsqrt4+h^2-2h-lim_...dfracsqrt1+h^2-1h=0-0$$ on rationalization of the numerators






                  share|cite|improve this answer
























                    up vote
                    1
                    down vote













                    Set $1/n=h^2$



                    $$lim_hto0^+dfracsqrt4+h^2-1-sqrt1+h^2h$$



                    $$=lim_...dfracsqrt4+h^2-2h-lim_...dfracsqrt1+h^2-1h=0-0$$ on rationalization of the numerators






                    share|cite|improve this answer






















                      up vote
                      1
                      down vote










                      up vote
                      1
                      down vote









                      Set $1/n=h^2$



                      $$lim_hto0^+dfracsqrt4+h^2-1-sqrt1+h^2h$$



                      $$=lim_...dfracsqrt4+h^2-2h-lim_...dfracsqrt1+h^2-1h=0-0$$ on rationalization of the numerators






                      share|cite|improve this answer












                      Set $1/n=h^2$



                      $$lim_hto0^+dfracsqrt4+h^2-1-sqrt1+h^2h$$



                      $$=lim_...dfracsqrt4+h^2-2h-lim_...dfracsqrt1+h^2-1h=0-0$$ on rationalization of the numerators







                      share|cite|improve this answer












                      share|cite|improve this answer



                      share|cite|improve this answer










                      answered 1 hour ago









                      lab bhattacharjee

                      216k14153267




                      216k14153267




















                          up vote
                          0
                          down vote













                          Write $$frac((sqrt4n+1-sqrtn+1)-sqrtn)((sqrt4n+1-sqrtn+1)+sqrtn)sqrt4n+1-sqrtn+1+sqrtn$$






                          share|cite|improve this answer
























                            up vote
                            0
                            down vote













                            Write $$frac((sqrt4n+1-sqrtn+1)-sqrtn)((sqrt4n+1-sqrtn+1)+sqrtn)sqrt4n+1-sqrtn+1+sqrtn$$






                            share|cite|improve this answer






















                              up vote
                              0
                              down vote










                              up vote
                              0
                              down vote









                              Write $$frac((sqrt4n+1-sqrtn+1)-sqrtn)((sqrt4n+1-sqrtn+1)+sqrtn)sqrt4n+1-sqrtn+1+sqrtn$$






                              share|cite|improve this answer












                              Write $$frac((sqrt4n+1-sqrtn+1)-sqrtn)((sqrt4n+1-sqrtn+1)+sqrtn)sqrt4n+1-sqrtn+1+sqrtn$$







                              share|cite|improve this answer












                              share|cite|improve this answer



                              share|cite|improve this answer










                              answered 2 hours ago









                              Dr. Sonnhard Graubner

                              69.8k32863




                              69.8k32863




















                                  up vote
                                  0
                                  down vote













                                  $sqrt4n+1-(sqrtn+sqrtn+1)<sqrt4n+1-2sqrtn=sqrt4n+1-sqrt4n
                                  <frac1sqrt4n+1+sqrt4nto0$



                                  So, the original limit is $0$.






                                  share|cite|improve this answer








                                  New contributor




                                  Yuyi Zhang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                                    up vote
                                    0
                                    down vote













                                    $sqrt4n+1-(sqrtn+sqrtn+1)<sqrt4n+1-2sqrtn=sqrt4n+1-sqrt4n
                                    <frac1sqrt4n+1+sqrt4nto0$



                                    So, the original limit is $0$.






                                    share|cite|improve this answer








                                    New contributor




                                    Yuyi Zhang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                    Check out our Code of Conduct.



















                                      up vote
                                      0
                                      down vote










                                      up vote
                                      0
                                      down vote









                                      $sqrt4n+1-(sqrtn+sqrtn+1)<sqrt4n+1-2sqrtn=sqrt4n+1-sqrt4n
                                      <frac1sqrt4n+1+sqrt4nto0$



                                      So, the original limit is $0$.






                                      share|cite|improve this answer








                                      New contributor




                                      Yuyi Zhang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                      Check out our Code of Conduct.









                                      $sqrt4n+1-(sqrtn+sqrtn+1)<sqrt4n+1-2sqrtn=sqrt4n+1-sqrt4n
                                      <frac1sqrt4n+1+sqrt4nto0$



                                      So, the original limit is $0$.







                                      share|cite|improve this answer








                                      New contributor




                                      Yuyi Zhang is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                                      share|cite|improve this answer



                                      share|cite|improve this answer






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                                      answered 1 hour ago









                                      Yuyi Zhang

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