Determine this limitIs my solution for divergence of $int_0^infty fracsin^10x ln xsqrtx$ correct?Limit involving the Riemann zeta function, why is this identity trivial?Show by comparison that $sumlimits_n=1^infty sin(frac1n)$ diverges?Determine con-/divergence of $sumlimits_n=1^infty left[ sqrtn^3+1 - n^frac32 right]$ by (limit) comparison testcomparison or limit comparison test..?Incorrect comparison test on seriesDetermine whether the series converges or diverges.How to determine the convergence of $sum frac 1 n!left(frac n eright)^n$ using Raabe's testLimit Comparison Test for integralWhy do I have to use L'Hopital in limit comparison test for $sum_n=1^infty sinleft(frac1nright)$Find whether a series is divergent or convergent with using the Limit Comparison Test

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Determine this limit


Is my solution for divergence of $int_0^infty fracsin^10x ln xsqrtx$ correct?Limit involving the Riemann zeta function, why is this identity trivial?Show by comparison that $sumlimits_n=1^infty sin(frac1n)$ diverges?Determine con-/divergence of $sumlimits_n=1^infty left[ sqrtn^3+1 - n^frac32 right]$ by (limit) comparison testcomparison or limit comparison test..?Incorrect comparison test on seriesDetermine whether the series converges or diverges.How to determine the convergence of $sum frac 1 n!left(frac n eright)^n$ using Raabe's testLimit Comparison Test for integralWhy do I have to use L'Hopital in limit comparison test for $sum_n=1^infty sinleft(frac1nright)$Find whether a series is divergent or convergent with using the Limit Comparison Test













2












$begingroup$


how can I determine the following limit? $$lim_ntoinfty fraclnleft(frac3pi4 + 2nright)-lnleft(fracpi4+2nright)ln(2n+2)-ln(2n).$$



This question stems from this question. The proof presented there is incorrect, and it would be trivial to show that the mentioned integral diverges if the above limit is $>0$ by using the comparison test (anyone feel free to do this by the way).










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  • 1




    $begingroup$
    Remember... $ln(a)-ln(b)=ln(frac ab)$.
    $endgroup$
    – manooooh
    1 hour ago






  • 1




    $begingroup$
    Welcome to math.SE!!
    $endgroup$
    – manooooh
    1 hour ago















2












$begingroup$


how can I determine the following limit? $$lim_ntoinfty fraclnleft(frac3pi4 + 2nright)-lnleft(fracpi4+2nright)ln(2n+2)-ln(2n).$$



This question stems from this question. The proof presented there is incorrect, and it would be trivial to show that the mentioned integral diverges if the above limit is $>0$ by using the comparison test (anyone feel free to do this by the way).










share|cite|improve this question









New contributor



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






$endgroup$







  • 1




    $begingroup$
    Remember... $ln(a)-ln(b)=ln(frac ab)$.
    $endgroup$
    – manooooh
    1 hour ago






  • 1




    $begingroup$
    Welcome to math.SE!!
    $endgroup$
    – manooooh
    1 hour ago













2












2








2





$begingroup$


how can I determine the following limit? $$lim_ntoinfty fraclnleft(frac3pi4 + 2nright)-lnleft(fracpi4+2nright)ln(2n+2)-ln(2n).$$



This question stems from this question. The proof presented there is incorrect, and it would be trivial to show that the mentioned integral diverges if the above limit is $>0$ by using the comparison test (anyone feel free to do this by the way).










share|cite|improve this question









New contributor



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






$endgroup$




how can I determine the following limit? $$lim_ntoinfty fraclnleft(frac3pi4 + 2nright)-lnleft(fracpi4+2nright)ln(2n+2)-ln(2n).$$



This question stems from this question. The proof presented there is incorrect, and it would be trivial to show that the mentioned integral diverges if the above limit is $>0$ by using the comparison test (anyone feel free to do this by the way).







sequences-and-series limits






share|cite|improve this question









New contributor



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










share|cite|improve this question









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Acacia Marsh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited 1 hour ago









El Ectric

353214




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asked 2 hours ago









Acacia MarshAcacia Marsh

155




155




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  • 1




    $begingroup$
    Remember... $ln(a)-ln(b)=ln(frac ab)$.
    $endgroup$
    – manooooh
    1 hour ago






  • 1




    $begingroup$
    Welcome to math.SE!!
    $endgroup$
    – manooooh
    1 hour ago












  • 1




    $begingroup$
    Remember... $ln(a)-ln(b)=ln(frac ab)$.
    $endgroup$
    – manooooh
    1 hour ago






  • 1




    $begingroup$
    Welcome to math.SE!!
    $endgroup$
    – manooooh
    1 hour ago







1




1




$begingroup$
Remember... $ln(a)-ln(b)=ln(frac ab)$.
$endgroup$
– manooooh
1 hour ago




$begingroup$
Remember... $ln(a)-ln(b)=ln(frac ab)$.
$endgroup$
– manooooh
1 hour ago




1




1




$begingroup$
Welcome to math.SE!!
$endgroup$
– manooooh
1 hour ago




$begingroup$
Welcome to math.SE!!
$endgroup$
– manooooh
1 hour ago










3 Answers
3






active

oldest

votes


















4












$begingroup$

Use l'Hôpital (and some logarithm identities) to get:



beginequation
beginsplit
lim_ntoinfty fracln(frac34 pi + 2n)-ln(fracpi4+2n)ln(2n+2)-ln(2n)
&= lim_ntoinfty fracln(3-frac16n8n+pi)ln(1+frac1n) \
&oversettextl'Hôpital= 16pi lim_ntoinfty fracn(n+1)(8n+pi)(8n+3pi) \
&oversettextlinearity of the limit=16pi bigg(lim_ntoinftyfrac n8n+pibigg)bigg(lim_ntoinftyfracn+18n+3pibigg) \
&= 16picdotfrac18cdotfrac18=fracpi4.
endsplit
endequation






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  • $begingroup$
    That's nice! Thanks
    $endgroup$
    – Acacia Marsh
    1 hour ago


















3












$begingroup$

Let $f(x)=lnleft(frac3pi3+xright)-lnleft(fracpi3+xright)$ and $g(x)=ln(x+2)-ln x$. Thenbeginalignlim_xtoinftyfracf(x)g(x)&=lim_xtoinftyfracf'(x)g'(x)\&=lim_xtoinftyfrac-frac8 pi (4 x+pi ) (4 x+3 pi )-frac2x^2+2 x\&=lim_xtoinftyfrac4pi(x^2+2x)(4 x+pi ) (4 x+3 pi )\&=fracpi4.endalignSo, your limit is $fracpi4$.






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  • $begingroup$
    Thank you! I like it
    $endgroup$
    – Acacia Marsh
    1 hour ago


















3












$begingroup$

Using the rules of logarithm so write $$fraclnleft(fracfrac5pi4+2nfracpi4+2nright)lnleft(frac2n+22nright)$$






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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    4












    $begingroup$

    Use l'Hôpital (and some logarithm identities) to get:



    beginequation
    beginsplit
    lim_ntoinfty fracln(frac34 pi + 2n)-ln(fracpi4+2n)ln(2n+2)-ln(2n)
    &= lim_ntoinfty fracln(3-frac16n8n+pi)ln(1+frac1n) \
    &oversettextl'Hôpital= 16pi lim_ntoinfty fracn(n+1)(8n+pi)(8n+3pi) \
    &oversettextlinearity of the limit=16pi bigg(lim_ntoinftyfrac n8n+pibigg)bigg(lim_ntoinftyfracn+18n+3pibigg) \
    &= 16picdotfrac18cdotfrac18=fracpi4.
    endsplit
    endequation






    share|cite|improve this answer









    $endgroup$












    • $begingroup$
      That's nice! Thanks
      $endgroup$
      – Acacia Marsh
      1 hour ago















    4












    $begingroup$

    Use l'Hôpital (and some logarithm identities) to get:



    beginequation
    beginsplit
    lim_ntoinfty fracln(frac34 pi + 2n)-ln(fracpi4+2n)ln(2n+2)-ln(2n)
    &= lim_ntoinfty fracln(3-frac16n8n+pi)ln(1+frac1n) \
    &oversettextl'Hôpital= 16pi lim_ntoinfty fracn(n+1)(8n+pi)(8n+3pi) \
    &oversettextlinearity of the limit=16pi bigg(lim_ntoinftyfrac n8n+pibigg)bigg(lim_ntoinftyfracn+18n+3pibigg) \
    &= 16picdotfrac18cdotfrac18=fracpi4.
    endsplit
    endequation






    share|cite|improve this answer









    $endgroup$












    • $begingroup$
      That's nice! Thanks
      $endgroup$
      – Acacia Marsh
      1 hour ago













    4












    4








    4





    $begingroup$

    Use l'Hôpital (and some logarithm identities) to get:



    beginequation
    beginsplit
    lim_ntoinfty fracln(frac34 pi + 2n)-ln(fracpi4+2n)ln(2n+2)-ln(2n)
    &= lim_ntoinfty fracln(3-frac16n8n+pi)ln(1+frac1n) \
    &oversettextl'Hôpital= 16pi lim_ntoinfty fracn(n+1)(8n+pi)(8n+3pi) \
    &oversettextlinearity of the limit=16pi bigg(lim_ntoinftyfrac n8n+pibigg)bigg(lim_ntoinftyfracn+18n+3pibigg) \
    &= 16picdotfrac18cdotfrac18=fracpi4.
    endsplit
    endequation






    share|cite|improve this answer









    $endgroup$



    Use l'Hôpital (and some logarithm identities) to get:



    beginequation
    beginsplit
    lim_ntoinfty fracln(frac34 pi + 2n)-ln(fracpi4+2n)ln(2n+2)-ln(2n)
    &= lim_ntoinfty fracln(3-frac16n8n+pi)ln(1+frac1n) \
    &oversettextl'Hôpital= 16pi lim_ntoinfty fracn(n+1)(8n+pi)(8n+3pi) \
    &oversettextlinearity of the limit=16pi bigg(lim_ntoinftyfrac n8n+pibigg)bigg(lim_ntoinftyfracn+18n+3pibigg) \
    &= 16picdotfrac18cdotfrac18=fracpi4.
    endsplit
    endequation







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered 1 hour ago









    Maximilian JanischMaximilian Janisch

    1,24017




    1,24017











    • $begingroup$
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      $endgroup$
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      1 hour ago
















    • $begingroup$
      That's nice! Thanks
      $endgroup$
      – Acacia Marsh
      1 hour ago















    $begingroup$
    That's nice! Thanks
    $endgroup$
    – Acacia Marsh
    1 hour ago




    $begingroup$
    That's nice! Thanks
    $endgroup$
    – Acacia Marsh
    1 hour ago











    3












    $begingroup$

    Let $f(x)=lnleft(frac3pi3+xright)-lnleft(fracpi3+xright)$ and $g(x)=ln(x+2)-ln x$. Thenbeginalignlim_xtoinftyfracf(x)g(x)&=lim_xtoinftyfracf'(x)g'(x)\&=lim_xtoinftyfrac-frac8 pi (4 x+pi ) (4 x+3 pi )-frac2x^2+2 x\&=lim_xtoinftyfrac4pi(x^2+2x)(4 x+pi ) (4 x+3 pi )\&=fracpi4.endalignSo, your limit is $fracpi4$.






    share|cite|improve this answer









    $endgroup$












    • $begingroup$
      Thank you! I like it
      $endgroup$
      – Acacia Marsh
      1 hour ago















    3












    $begingroup$

    Let $f(x)=lnleft(frac3pi3+xright)-lnleft(fracpi3+xright)$ and $g(x)=ln(x+2)-ln x$. Thenbeginalignlim_xtoinftyfracf(x)g(x)&=lim_xtoinftyfracf'(x)g'(x)\&=lim_xtoinftyfrac-frac8 pi (4 x+pi ) (4 x+3 pi )-frac2x^2+2 x\&=lim_xtoinftyfrac4pi(x^2+2x)(4 x+pi ) (4 x+3 pi )\&=fracpi4.endalignSo, your limit is $fracpi4$.






    share|cite|improve this answer









    $endgroup$












    • $begingroup$
      Thank you! I like it
      $endgroup$
      – Acacia Marsh
      1 hour ago













    3












    3








    3





    $begingroup$

    Let $f(x)=lnleft(frac3pi3+xright)-lnleft(fracpi3+xright)$ and $g(x)=ln(x+2)-ln x$. Thenbeginalignlim_xtoinftyfracf(x)g(x)&=lim_xtoinftyfracf'(x)g'(x)\&=lim_xtoinftyfrac-frac8 pi (4 x+pi ) (4 x+3 pi )-frac2x^2+2 x\&=lim_xtoinftyfrac4pi(x^2+2x)(4 x+pi ) (4 x+3 pi )\&=fracpi4.endalignSo, your limit is $fracpi4$.






    share|cite|improve this answer









    $endgroup$



    Let $f(x)=lnleft(frac3pi3+xright)-lnleft(fracpi3+xright)$ and $g(x)=ln(x+2)-ln x$. Thenbeginalignlim_xtoinftyfracf(x)g(x)&=lim_xtoinftyfracf'(x)g'(x)\&=lim_xtoinftyfrac-frac8 pi (4 x+pi ) (4 x+3 pi )-frac2x^2+2 x\&=lim_xtoinftyfrac4pi(x^2+2x)(4 x+pi ) (4 x+3 pi )\&=fracpi4.endalignSo, your limit is $fracpi4$.







    share|cite|improve this answer












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    answered 1 hour ago









    José Carlos SantosJosé Carlos Santos

    186k24145259




    186k24145259











    • $begingroup$
      Thank you! I like it
      $endgroup$
      – Acacia Marsh
      1 hour ago
















    • $begingroup$
      Thank you! I like it
      $endgroup$
      – Acacia Marsh
      1 hour ago















    $begingroup$
    Thank you! I like it
    $endgroup$
    – Acacia Marsh
    1 hour ago




    $begingroup$
    Thank you! I like it
    $endgroup$
    – Acacia Marsh
    1 hour ago











    3












    $begingroup$

    Using the rules of logarithm so write $$fraclnleft(fracfrac5pi4+2nfracpi4+2nright)lnleft(frac2n+22nright)$$






    share|cite|improve this answer











    $endgroup$

















      3












      $begingroup$

      Using the rules of logarithm so write $$fraclnleft(fracfrac5pi4+2nfracpi4+2nright)lnleft(frac2n+22nright)$$






      share|cite|improve this answer











      $endgroup$















        3












        3








        3





        $begingroup$

        Using the rules of logarithm so write $$fraclnleft(fracfrac5pi4+2nfracpi4+2nright)lnleft(frac2n+22nright)$$






        share|cite|improve this answer











        $endgroup$



        Using the rules of logarithm so write $$fraclnleft(fracfrac5pi4+2nfracpi4+2nright)lnleft(frac2n+22nright)$$







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited 1 hour ago









        user10354138

        10.1k21025




        10.1k21025










        answered 1 hour ago









        Dr. Sonnhard GraubnerDr. Sonnhard Graubner

        81.1k42867




        81.1k42867




















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