limit of $limlimits_{x to infty}((x+1)^a - x^a)$ [on hold]











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Hello everybody, i couldn't figure out how to demonstrate this equation without L'Hopital i wonder if its possible.




$a in (0,1)$
$limlimits_{x to infty}((x+1)^a - x^a) = 0$










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put on hold as off-topic by TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh Nov 25 at 11:19


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh

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    I'd use MVT.${}$
    – Lord Shark the Unknown
    Nov 18 at 20:05















up vote
-3
down vote

favorite













Hello everybody, i couldn't figure out how to demonstrate this equation without L'Hopital i wonder if its possible.




$a in (0,1)$
$limlimits_{x to infty}((x+1)^a - x^a) = 0$










share|cite|improve this question













put on hold as off-topic by TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh Nov 25 at 11:19


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh

If this question can be reworded to fit the rules in the help center, please edit the question.









  • 1




    I'd use MVT.${}$
    – Lord Shark the Unknown
    Nov 18 at 20:05













up vote
-3
down vote

favorite









up vote
-3
down vote

favorite












Hello everybody, i couldn't figure out how to demonstrate this equation without L'Hopital i wonder if its possible.




$a in (0,1)$
$limlimits_{x to infty}((x+1)^a - x^a) = 0$










share|cite|improve this question














Hello everybody, i couldn't figure out how to demonstrate this equation without L'Hopital i wonder if its possible.




$a in (0,1)$
$limlimits_{x to infty}((x+1)^a - x^a) = 0$







calculus






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asked Nov 18 at 19:59









Eray Xx

85




85




put on hold as off-topic by TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh Nov 25 at 11:19


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh

If this question can be reworded to fit the rules in the help center, please edit the question.




put on hold as off-topic by TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh Nov 25 at 11:19


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – TheSimpliFire, Holo, Did, José Carlos Santos, Brahadeesh

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 1




    I'd use MVT.${}$
    – Lord Shark the Unknown
    Nov 18 at 20:05














  • 1




    I'd use MVT.${}$
    – Lord Shark the Unknown
    Nov 18 at 20:05








1




1




I'd use MVT.${}$
– Lord Shark the Unknown
Nov 18 at 20:05




I'd use MVT.${}$
– Lord Shark the Unknown
Nov 18 at 20:05










2 Answers
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With Bernoulli's inequality
$$0leq x^a(1+frac1x)^a-x^aleq x^aleft(1+dfrac{a}{x}right)-x^ato0$$
as $xtoinfty$.






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    By applying a Taylor expansion, as $u to 0$, one gets
    $$
    left( 1+uright)^a=1+au+o(u)
    $$
    Then one may write, as $x to infty$,
    $$
    (x+1)^a - x^a=x^a left[left(1+frac 1xright)^a-1 right]=x^a left[left(1+frac {a}x+oleft(frac1x right)right)-1 right]=ax^{a-1}+oleft(x^{a-1} right)
    $$
    which tends to $0$ since $a in (0,1)$.






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      2 Answers
      2






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      oldest

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      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

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      active

      oldest

      votes








      up vote
      2
      down vote













      With Bernoulli's inequality
      $$0leq x^a(1+frac1x)^a-x^aleq x^aleft(1+dfrac{a}{x}right)-x^ato0$$
      as $xtoinfty$.






      share|cite|improve this answer

























        up vote
        2
        down vote













        With Bernoulli's inequality
        $$0leq x^a(1+frac1x)^a-x^aleq x^aleft(1+dfrac{a}{x}right)-x^ato0$$
        as $xtoinfty$.






        share|cite|improve this answer























          up vote
          2
          down vote










          up vote
          2
          down vote









          With Bernoulli's inequality
          $$0leq x^a(1+frac1x)^a-x^aleq x^aleft(1+dfrac{a}{x}right)-x^ato0$$
          as $xtoinfty$.






          share|cite|improve this answer












          With Bernoulli's inequality
          $$0leq x^a(1+frac1x)^a-x^aleq x^aleft(1+dfrac{a}{x}right)-x^ato0$$
          as $xtoinfty$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 18 at 20:05









          Nosrati

          1




          1






















              up vote
              2
              down vote













              By applying a Taylor expansion, as $u to 0$, one gets
              $$
              left( 1+uright)^a=1+au+o(u)
              $$
              Then one may write, as $x to infty$,
              $$
              (x+1)^a - x^a=x^a left[left(1+frac 1xright)^a-1 right]=x^a left[left(1+frac {a}x+oleft(frac1x right)right)-1 right]=ax^{a-1}+oleft(x^{a-1} right)
              $$
              which tends to $0$ since $a in (0,1)$.






              share|cite|improve this answer

























                up vote
                2
                down vote













                By applying a Taylor expansion, as $u to 0$, one gets
                $$
                left( 1+uright)^a=1+au+o(u)
                $$
                Then one may write, as $x to infty$,
                $$
                (x+1)^a - x^a=x^a left[left(1+frac 1xright)^a-1 right]=x^a left[left(1+frac {a}x+oleft(frac1x right)right)-1 right]=ax^{a-1}+oleft(x^{a-1} right)
                $$
                which tends to $0$ since $a in (0,1)$.






                share|cite|improve this answer























                  up vote
                  2
                  down vote










                  up vote
                  2
                  down vote









                  By applying a Taylor expansion, as $u to 0$, one gets
                  $$
                  left( 1+uright)^a=1+au+o(u)
                  $$
                  Then one may write, as $x to infty$,
                  $$
                  (x+1)^a - x^a=x^a left[left(1+frac 1xright)^a-1 right]=x^a left[left(1+frac {a}x+oleft(frac1x right)right)-1 right]=ax^{a-1}+oleft(x^{a-1} right)
                  $$
                  which tends to $0$ since $a in (0,1)$.






                  share|cite|improve this answer












                  By applying a Taylor expansion, as $u to 0$, one gets
                  $$
                  left( 1+uright)^a=1+au+o(u)
                  $$
                  Then one may write, as $x to infty$,
                  $$
                  (x+1)^a - x^a=x^a left[left(1+frac 1xright)^a-1 right]=x^a left[left(1+frac {a}x+oleft(frac1x right)right)-1 right]=ax^{a-1}+oleft(x^{a-1} right)
                  $$
                  which tends to $0$ since $a in (0,1)$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Nov 18 at 20:06









                  Olivier Oloa

                  107k17175293




                  107k17175293















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