Find the limit $limlimits_{n to infty}sum_{k=1}^n frac{sqrt{4n+5k}}{n sqrt{n}} $












1












$begingroup$


I got stuck on the following limit:



$limlimits_{n to infty}5sum_{k=1}^n frac{sqrt{4n+5k}}{n sqrt{n}} $



The expected answer is $frac{38}{15}.$ Any hint is appreciated. Thanks



EDIT: The task is from this polish textbook (http://lucc.pl/inf/analiza_1/gewert_skoczylas__analiza_matematyczna_1__definicje_twierdzenia_wzory.pdf). It's on page 166 of the book (ex. 8.4.3 h). I want to compute this using the above fact. It's a book for first year students.










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  • $begingroup$
    If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
    $endgroup$
    – Stefan Lafon
    Jan 25 at 20:12










  • $begingroup$
    Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
    $endgroup$
    – The Cat
    Jan 25 at 20:15
















1












$begingroup$


I got stuck on the following limit:



$limlimits_{n to infty}5sum_{k=1}^n frac{sqrt{4n+5k}}{n sqrt{n}} $



The expected answer is $frac{38}{15}.$ Any hint is appreciated. Thanks



EDIT: The task is from this polish textbook (http://lucc.pl/inf/analiza_1/gewert_skoczylas__analiza_matematyczna_1__definicje_twierdzenia_wzory.pdf). It's on page 166 of the book (ex. 8.4.3 h). I want to compute this using the above fact. It's a book for first year students.










share|cite|improve this question











$endgroup$












  • $begingroup$
    If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
    $endgroup$
    – Stefan Lafon
    Jan 25 at 20:12










  • $begingroup$
    Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
    $endgroup$
    – The Cat
    Jan 25 at 20:15














1












1








1





$begingroup$


I got stuck on the following limit:



$limlimits_{n to infty}5sum_{k=1}^n frac{sqrt{4n+5k}}{n sqrt{n}} $



The expected answer is $frac{38}{15}.$ Any hint is appreciated. Thanks



EDIT: The task is from this polish textbook (http://lucc.pl/inf/analiza_1/gewert_skoczylas__analiza_matematyczna_1__definicje_twierdzenia_wzory.pdf). It's on page 166 of the book (ex. 8.4.3 h). I want to compute this using the above fact. It's a book for first year students.










share|cite|improve this question











$endgroup$




I got stuck on the following limit:



$limlimits_{n to infty}5sum_{k=1}^n frac{sqrt{4n+5k}}{n sqrt{n}} $



The expected answer is $frac{38}{15}.$ Any hint is appreciated. Thanks



EDIT: The task is from this polish textbook (http://lucc.pl/inf/analiza_1/gewert_skoczylas__analiza_matematyczna_1__definicje_twierdzenia_wzory.pdf). It's on page 166 of the book (ex. 8.4.3 h). I want to compute this using the above fact. It's a book for first year students.







limits summation






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edited Jan 25 at 22:32







The Cat

















asked Jan 25 at 20:09









The CatThe Cat

33815




33815












  • $begingroup$
    If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
    $endgroup$
    – Stefan Lafon
    Jan 25 at 20:12










  • $begingroup$
    Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
    $endgroup$
    – The Cat
    Jan 25 at 20:15


















  • $begingroup$
    If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
    $endgroup$
    – Stefan Lafon
    Jan 25 at 20:12










  • $begingroup$
    Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
    $endgroup$
    – The Cat
    Jan 25 at 20:15
















$begingroup$
If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
$endgroup$
– Stefan Lafon
Jan 25 at 20:12




$begingroup$
If you rearrange the terms a bit, this is a Riemann sum. So it converges to some integral. Can you take it from there?
$endgroup$
– Stefan Lafon
Jan 25 at 20:12












$begingroup$
Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
$endgroup$
– The Cat
Jan 25 at 20:15




$begingroup$
Well this task here is from a prep-book to college. I've just started calculating definite integrals by definition, and in order to do the exercise i need to find this limit. I should be something way simpler.
$endgroup$
– The Cat
Jan 25 at 20:15










1 Answer
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$begingroup$

Hint (Riemman Sum-Integral) :



$$lim_{n to infty} sum_{k=1}^n frac{sqrt{4n+5k}}{nsqrt{n}} = lim_{n to infty} frac{1}{n} sum_{k=1}^n sqrt{4 + 5frac{k}{n}} = int_0^1 sqrt{4 + 5x} ;mathrm{d}x$$






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    1 Answer
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    1 Answer
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    $begingroup$

    Hint (Riemman Sum-Integral) :



    $$lim_{n to infty} sum_{k=1}^n frac{sqrt{4n+5k}}{nsqrt{n}} = lim_{n to infty} frac{1}{n} sum_{k=1}^n sqrt{4 + 5frac{k}{n}} = int_0^1 sqrt{4 + 5x} ;mathrm{d}x$$






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      Hint (Riemman Sum-Integral) :



      $$lim_{n to infty} sum_{k=1}^n frac{sqrt{4n+5k}}{nsqrt{n}} = lim_{n to infty} frac{1}{n} sum_{k=1}^n sqrt{4 + 5frac{k}{n}} = int_0^1 sqrt{4 + 5x} ;mathrm{d}x$$






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        Hint (Riemman Sum-Integral) :



        $$lim_{n to infty} sum_{k=1}^n frac{sqrt{4n+5k}}{nsqrt{n}} = lim_{n to infty} frac{1}{n} sum_{k=1}^n sqrt{4 + 5frac{k}{n}} = int_0^1 sqrt{4 + 5x} ;mathrm{d}x$$






        share|cite|improve this answer









        $endgroup$



        Hint (Riemman Sum-Integral) :



        $$lim_{n to infty} sum_{k=1}^n frac{sqrt{4n+5k}}{nsqrt{n}} = lim_{n to infty} frac{1}{n} sum_{k=1}^n sqrt{4 + 5frac{k}{n}} = int_0^1 sqrt{4 + 5x} ;mathrm{d}x$$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 25 at 20:12









        RebellosRebellos

        15.4k31250




        15.4k31250






























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