What is the limit of $lim_{xtoinfty}...












2












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Hi I have problem to evaluate this limit:



$$lim_{xtoinfty} sin^2{(frac{1}{n^{48}})}((n+frac{1}{n^3})^{100}-(n^{32}+n^{10}+1)^3-n^{100}).$$



I tried to use the binomial theorem and tried to subtract the n with power hundred, but I am really struggling.



I can get to something like:



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(n^{100}+sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3 -n^{100})$



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3)$



and from here I am stucky really, I am not even sure if these steps before were somewhat helpful.










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  • 1




    $begingroup$
    You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
    $endgroup$
    – Peter Foreman
    Feb 1 at 20:59












  • $begingroup$
    Everywhere you have $x$ it should be $n$.
    $endgroup$
    – symplectomorphic
    Feb 1 at 21:19
















2












$begingroup$


Hi I have problem to evaluate this limit:



$$lim_{xtoinfty} sin^2{(frac{1}{n^{48}})}((n+frac{1}{n^3})^{100}-(n^{32}+n^{10}+1)^3-n^{100}).$$



I tried to use the binomial theorem and tried to subtract the n with power hundred, but I am really struggling.



I can get to something like:



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(n^{100}+sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3 -n^{100})$



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3)$



and from here I am stucky really, I am not even sure if these steps before were somewhat helpful.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
    $endgroup$
    – Peter Foreman
    Feb 1 at 20:59












  • $begingroup$
    Everywhere you have $x$ it should be $n$.
    $endgroup$
    – symplectomorphic
    Feb 1 at 21:19














2












2








2


1



$begingroup$


Hi I have problem to evaluate this limit:



$$lim_{xtoinfty} sin^2{(frac{1}{n^{48}})}((n+frac{1}{n^3})^{100}-(n^{32}+n^{10}+1)^3-n^{100}).$$



I tried to use the binomial theorem and tried to subtract the n with power hundred, but I am really struggling.



I can get to something like:



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(n^{100}+sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3 -n^{100})$



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3)$



and from here I am stucky really, I am not even sure if these steps before were somewhat helpful.










share|cite|improve this question











$endgroup$




Hi I have problem to evaluate this limit:



$$lim_{xtoinfty} sin^2{(frac{1}{n^{48}})}((n+frac{1}{n^3})^{100}-(n^{32}+n^{10}+1)^3-n^{100}).$$



I tried to use the binomial theorem and tried to subtract the n with power hundred, but I am really struggling.



I can get to something like:



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(n^{100}+sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3 -n^{100})$



$lim_{xtoinfty} sin^2{(dfrac{1}{n^{48}})}(sum_{i=0}^{99}binom{99}{i}n^{99-j}(dfrac{1}{n^3})^j - (n^{42}+1)^3)$



and from here I am stucky really, I am not even sure if these steps before were somewhat helpful.







calculus limits






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edited Feb 1 at 21:09









Robert Z

101k1072145




101k1072145










asked Feb 1 at 20:51









cris14cris14

1338




1338








  • 1




    $begingroup$
    You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
    $endgroup$
    – Peter Foreman
    Feb 1 at 20:59












  • $begingroup$
    Everywhere you have $x$ it should be $n$.
    $endgroup$
    – symplectomorphic
    Feb 1 at 21:19














  • 1




    $begingroup$
    You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
    $endgroup$
    – Peter Foreman
    Feb 1 at 20:59












  • $begingroup$
    Everywhere you have $x$ it should be $n$.
    $endgroup$
    – symplectomorphic
    Feb 1 at 21:19








1




1




$begingroup$
You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
$endgroup$
– Peter Foreman
Feb 1 at 20:59






$begingroup$
You cannot add $n^{32}$ and $n^{10}$ to get $n^{42}$
$endgroup$
– Peter Foreman
Feb 1 at 20:59














$begingroup$
Everywhere you have $x$ it should be $n$.
$endgroup$
– symplectomorphic
Feb 1 at 21:19




$begingroup$
Everywhere you have $x$ it should be $n$.
$endgroup$
– symplectomorphic
Feb 1 at 21:19










2 Answers
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$begingroup$

Hint. Note that you need just a small part of the two expansions:
$$left(n+dfrac{1}{n^3}right)^{100}=n^{100}+100n^{96}+o(n^{96}),$$
and
$$(n^{32}+n^{10}+1)^3=n^{96}+ o(n^{96}).$$
Can you take it from here?



P.S. The binomial coefficient in your first expansion should be $binom{100}{i}$.






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    0












    $begingroup$

    Since by Taylor expansion for $n rightarrow infty, sinleft( frac{1}{n^{48}} right) approx frac{1}{n^{48}}$, a good idea is to consider only the terms of degree greater than or equal to 96, since the others goes to 0. Hence the limit shall be
    $$lim_{n rightarrow infty} sin^2 left( frac{1}{n^{48}}right)left ( left ( n + frac{1}{n^3} right)^{100} - left( n^{32} + n^{10} +1 right)^3 - n^{100} right) = \
    = lim_{n rightarrow infty} frac{1}{n^{96}} left( n^{100} + {{100}choose{1}} n^{96} - n^{96} - n^{100}right) = {{100}choose{1}} - 1 $$






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      2 Answers
      2






      active

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      2 Answers
      2






      active

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      active

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      0












      $begingroup$

      Hint. Note that you need just a small part of the two expansions:
      $$left(n+dfrac{1}{n^3}right)^{100}=n^{100}+100n^{96}+o(n^{96}),$$
      and
      $$(n^{32}+n^{10}+1)^3=n^{96}+ o(n^{96}).$$
      Can you take it from here?



      P.S. The binomial coefficient in your first expansion should be $binom{100}{i}$.






      share|cite|improve this answer









      $endgroup$


















        0












        $begingroup$

        Hint. Note that you need just a small part of the two expansions:
        $$left(n+dfrac{1}{n^3}right)^{100}=n^{100}+100n^{96}+o(n^{96}),$$
        and
        $$(n^{32}+n^{10}+1)^3=n^{96}+ o(n^{96}).$$
        Can you take it from here?



        P.S. The binomial coefficient in your first expansion should be $binom{100}{i}$.






        share|cite|improve this answer









        $endgroup$
















          0












          0








          0





          $begingroup$

          Hint. Note that you need just a small part of the two expansions:
          $$left(n+dfrac{1}{n^3}right)^{100}=n^{100}+100n^{96}+o(n^{96}),$$
          and
          $$(n^{32}+n^{10}+1)^3=n^{96}+ o(n^{96}).$$
          Can you take it from here?



          P.S. The binomial coefficient in your first expansion should be $binom{100}{i}$.






          share|cite|improve this answer









          $endgroup$



          Hint. Note that you need just a small part of the two expansions:
          $$left(n+dfrac{1}{n^3}right)^{100}=n^{100}+100n^{96}+o(n^{96}),$$
          and
          $$(n^{32}+n^{10}+1)^3=n^{96}+ o(n^{96}).$$
          Can you take it from here?



          P.S. The binomial coefficient in your first expansion should be $binom{100}{i}$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Feb 1 at 21:00









          Robert ZRobert Z

          101k1072145




          101k1072145























              0












              $begingroup$

              Since by Taylor expansion for $n rightarrow infty, sinleft( frac{1}{n^{48}} right) approx frac{1}{n^{48}}$, a good idea is to consider only the terms of degree greater than or equal to 96, since the others goes to 0. Hence the limit shall be
              $$lim_{n rightarrow infty} sin^2 left( frac{1}{n^{48}}right)left ( left ( n + frac{1}{n^3} right)^{100} - left( n^{32} + n^{10} +1 right)^3 - n^{100} right) = \
              = lim_{n rightarrow infty} frac{1}{n^{96}} left( n^{100} + {{100}choose{1}} n^{96} - n^{96} - n^{100}right) = {{100}choose{1}} - 1 $$






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                Since by Taylor expansion for $n rightarrow infty, sinleft( frac{1}{n^{48}} right) approx frac{1}{n^{48}}$, a good idea is to consider only the terms of degree greater than or equal to 96, since the others goes to 0. Hence the limit shall be
                $$lim_{n rightarrow infty} sin^2 left( frac{1}{n^{48}}right)left ( left ( n + frac{1}{n^3} right)^{100} - left( n^{32} + n^{10} +1 right)^3 - n^{100} right) = \
                = lim_{n rightarrow infty} frac{1}{n^{96}} left( n^{100} + {{100}choose{1}} n^{96} - n^{96} - n^{100}right) = {{100}choose{1}} - 1 $$






                share|cite|improve this answer









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                  0












                  0








                  0





                  $begingroup$

                  Since by Taylor expansion for $n rightarrow infty, sinleft( frac{1}{n^{48}} right) approx frac{1}{n^{48}}$, a good idea is to consider only the terms of degree greater than or equal to 96, since the others goes to 0. Hence the limit shall be
                  $$lim_{n rightarrow infty} sin^2 left( frac{1}{n^{48}}right)left ( left ( n + frac{1}{n^3} right)^{100} - left( n^{32} + n^{10} +1 right)^3 - n^{100} right) = \
                  = lim_{n rightarrow infty} frac{1}{n^{96}} left( n^{100} + {{100}choose{1}} n^{96} - n^{96} - n^{100}right) = {{100}choose{1}} - 1 $$






                  share|cite|improve this answer









                  $endgroup$



                  Since by Taylor expansion for $n rightarrow infty, sinleft( frac{1}{n^{48}} right) approx frac{1}{n^{48}}$, a good idea is to consider only the terms of degree greater than or equal to 96, since the others goes to 0. Hence the limit shall be
                  $$lim_{n rightarrow infty} sin^2 left( frac{1}{n^{48}}right)left ( left ( n + frac{1}{n^3} right)^{100} - left( n^{32} + n^{10} +1 right)^3 - n^{100} right) = \
                  = lim_{n rightarrow infty} frac{1}{n^{96}} left( n^{100} + {{100}choose{1}} n^{96} - n^{96} - n^{100}right) = {{100}choose{1}} - 1 $$







                  share|cite|improve this answer












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                  share|cite|improve this answer










                  answered Feb 1 at 21:04









                  JCFJCF

                  356112




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