Find first five non-zero terms of power series












0












$begingroup$


I have the function f(x) = $dfrac{2x}{left(x-5right)^2}$, and I'm supposed to "find the first five non-zero terms of power series representation centered at x = 0."



Using $frac{f^{(n)}(0)}{n!}$, the first non-zero terms I get are:



C1 = 2/25



C2 = 4/125



C3 = 6/625



C4 = 8/3125



C5 = 2/3125



However, WebWork marks these as incorrect. Any alternative methods or corrections to the work above are gladly appreciated.










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  • $begingroup$
    those are the terms wolfram alpha gives.
    $endgroup$
    – Dando18
    Dec 8 '18 at 20:36










  • $begingroup$
    Does that mean the terms I listed are correct?
    $endgroup$
    – BOBBY SHMURDA
    Dec 8 '18 at 21:10










  • $begingroup$
    It seems so... Unless the question is asking for something else.
    $endgroup$
    – Dando18
    Dec 8 '18 at 21:54
















0












$begingroup$


I have the function f(x) = $dfrac{2x}{left(x-5right)^2}$, and I'm supposed to "find the first five non-zero terms of power series representation centered at x = 0."



Using $frac{f^{(n)}(0)}{n!}$, the first non-zero terms I get are:



C1 = 2/25



C2 = 4/125



C3 = 6/625



C4 = 8/3125



C5 = 2/3125



However, WebWork marks these as incorrect. Any alternative methods or corrections to the work above are gladly appreciated.










share|cite|improve this question









$endgroup$












  • $begingroup$
    those are the terms wolfram alpha gives.
    $endgroup$
    – Dando18
    Dec 8 '18 at 20:36










  • $begingroup$
    Does that mean the terms I listed are correct?
    $endgroup$
    – BOBBY SHMURDA
    Dec 8 '18 at 21:10










  • $begingroup$
    It seems so... Unless the question is asking for something else.
    $endgroup$
    – Dando18
    Dec 8 '18 at 21:54














0












0








0





$begingroup$


I have the function f(x) = $dfrac{2x}{left(x-5right)^2}$, and I'm supposed to "find the first five non-zero terms of power series representation centered at x = 0."



Using $frac{f^{(n)}(0)}{n!}$, the first non-zero terms I get are:



C1 = 2/25



C2 = 4/125



C3 = 6/625



C4 = 8/3125



C5 = 2/3125



However, WebWork marks these as incorrect. Any alternative methods or corrections to the work above are gladly appreciated.










share|cite|improve this question









$endgroup$




I have the function f(x) = $dfrac{2x}{left(x-5right)^2}$, and I'm supposed to "find the first five non-zero terms of power series representation centered at x = 0."



Using $frac{f^{(n)}(0)}{n!}$, the first non-zero terms I get are:



C1 = 2/25



C2 = 4/125



C3 = 6/625



C4 = 8/3125



C5 = 2/3125



However, WebWork marks these as incorrect. Any alternative methods or corrections to the work above are gladly appreciated.







calculus sequences-and-series power-series






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asked Dec 8 '18 at 20:25









BOBBY SHMURDABOBBY SHMURDA

102




102












  • $begingroup$
    those are the terms wolfram alpha gives.
    $endgroup$
    – Dando18
    Dec 8 '18 at 20:36










  • $begingroup$
    Does that mean the terms I listed are correct?
    $endgroup$
    – BOBBY SHMURDA
    Dec 8 '18 at 21:10










  • $begingroup$
    It seems so... Unless the question is asking for something else.
    $endgroup$
    – Dando18
    Dec 8 '18 at 21:54


















  • $begingroup$
    those are the terms wolfram alpha gives.
    $endgroup$
    – Dando18
    Dec 8 '18 at 20:36










  • $begingroup$
    Does that mean the terms I listed are correct?
    $endgroup$
    – BOBBY SHMURDA
    Dec 8 '18 at 21:10










  • $begingroup$
    It seems so... Unless the question is asking for something else.
    $endgroup$
    – Dando18
    Dec 8 '18 at 21:54
















$begingroup$
those are the terms wolfram alpha gives.
$endgroup$
– Dando18
Dec 8 '18 at 20:36




$begingroup$
those are the terms wolfram alpha gives.
$endgroup$
– Dando18
Dec 8 '18 at 20:36












$begingroup$
Does that mean the terms I listed are correct?
$endgroup$
– BOBBY SHMURDA
Dec 8 '18 at 21:10




$begingroup$
Does that mean the terms I listed are correct?
$endgroup$
– BOBBY SHMURDA
Dec 8 '18 at 21:10












$begingroup$
It seems so... Unless the question is asking for something else.
$endgroup$
– Dando18
Dec 8 '18 at 21:54




$begingroup$
It seems so... Unless the question is asking for something else.
$endgroup$
– Dando18
Dec 8 '18 at 21:54










1 Answer
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$begingroup$

Hint:



You don't have to compute the successive derivatives. Instead rewrite the fraction as
$$frac{2x}{left(x-5right)^2}=frac{2x}{25}frac 1{Bigl(1-cfrac x5Bigr)^2}=frac{2x}5left(frac 1{1-smash[b]{cfrac x5}}right)'$$
and use the power series expansion $;dfrac1{1-u}=1+u+u^2+dotsm$






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    1 Answer
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    active

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    1 Answer
    1






    active

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    active

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    active

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    0












    $begingroup$

    Hint:



    You don't have to compute the successive derivatives. Instead rewrite the fraction as
    $$frac{2x}{left(x-5right)^2}=frac{2x}{25}frac 1{Bigl(1-cfrac x5Bigr)^2}=frac{2x}5left(frac 1{1-smash[b]{cfrac x5}}right)'$$
    and use the power series expansion $;dfrac1{1-u}=1+u+u^2+dotsm$






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Hint:



      You don't have to compute the successive derivatives. Instead rewrite the fraction as
      $$frac{2x}{left(x-5right)^2}=frac{2x}{25}frac 1{Bigl(1-cfrac x5Bigr)^2}=frac{2x}5left(frac 1{1-smash[b]{cfrac x5}}right)'$$
      and use the power series expansion $;dfrac1{1-u}=1+u+u^2+dotsm$






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Hint:



        You don't have to compute the successive derivatives. Instead rewrite the fraction as
        $$frac{2x}{left(x-5right)^2}=frac{2x}{25}frac 1{Bigl(1-cfrac x5Bigr)^2}=frac{2x}5left(frac 1{1-smash[b]{cfrac x5}}right)'$$
        and use the power series expansion $;dfrac1{1-u}=1+u+u^2+dotsm$






        share|cite|improve this answer









        $endgroup$



        Hint:



        You don't have to compute the successive derivatives. Instead rewrite the fraction as
        $$frac{2x}{left(x-5right)^2}=frac{2x}{25}frac 1{Bigl(1-cfrac x5Bigr)^2}=frac{2x}5left(frac 1{1-smash[b]{cfrac x5}}right)'$$
        and use the power series expansion $;dfrac1{1-u}=1+u+u^2+dotsm$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 8 '18 at 20:58









        BernardBernard

        119k740113




        119k740113






























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