Finding Polynomial Roots Analytically












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Let us consider the following function: $$f(s_1,s_2,...s_n,n)=frac{1}{1+s_1}+frac{1}{(1+s_2)^2}+...+frac{1}{(1+s_n)^n},$$ where $s_iin(0,1), i=1,...,n.$
Let us introduce the following function: $$g(x,n)=frac{1}{1+x}+frac{1}{(1+x)^2}+...+frac{1}{(1+x)^n}.$$
We require that $f(s_1,s_2,...s_n,n)=g(x,n)$ and from this condition it is needed to find $x$. In other words it is needed to construct $x(s_1,...,s_n)$. Since $n$ attains large numbers (e.g. 25) according Abel-Ruffini theorem this problem isn't possible to solve analytically.



Please guide me how to find some approximation. Does iteration method a good way to solve the problem? (I mean saying iteration following: assign to $s_i$'s values, find $f(s_1,...s_n)$, therefore estimate $x$).










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  • $begingroup$
    $g(x, n)$ is a geometric progression, isn't it?
    $endgroup$
    – user58697
    Dec 1 '18 at 23:24










  • $begingroup$
    @user58697 Yes, $g(x,n)$ is a geometric progression.
    $endgroup$
    – David
    Dec 3 '18 at 5:58
















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$begingroup$


Let us consider the following function: $$f(s_1,s_2,...s_n,n)=frac{1}{1+s_1}+frac{1}{(1+s_2)^2}+...+frac{1}{(1+s_n)^n},$$ where $s_iin(0,1), i=1,...,n.$
Let us introduce the following function: $$g(x,n)=frac{1}{1+x}+frac{1}{(1+x)^2}+...+frac{1}{(1+x)^n}.$$
We require that $f(s_1,s_2,...s_n,n)=g(x,n)$ and from this condition it is needed to find $x$. In other words it is needed to construct $x(s_1,...,s_n)$. Since $n$ attains large numbers (e.g. 25) according Abel-Ruffini theorem this problem isn't possible to solve analytically.



Please guide me how to find some approximation. Does iteration method a good way to solve the problem? (I mean saying iteration following: assign to $s_i$'s values, find $f(s_1,...s_n)$, therefore estimate $x$).










share|cite|improve this question











$endgroup$












  • $begingroup$
    $g(x, n)$ is a geometric progression, isn't it?
    $endgroup$
    – user58697
    Dec 1 '18 at 23:24










  • $begingroup$
    @user58697 Yes, $g(x,n)$ is a geometric progression.
    $endgroup$
    – David
    Dec 3 '18 at 5:58














0












0








0


1



$begingroup$


Let us consider the following function: $$f(s_1,s_2,...s_n,n)=frac{1}{1+s_1}+frac{1}{(1+s_2)^2}+...+frac{1}{(1+s_n)^n},$$ where $s_iin(0,1), i=1,...,n.$
Let us introduce the following function: $$g(x,n)=frac{1}{1+x}+frac{1}{(1+x)^2}+...+frac{1}{(1+x)^n}.$$
We require that $f(s_1,s_2,...s_n,n)=g(x,n)$ and from this condition it is needed to find $x$. In other words it is needed to construct $x(s_1,...,s_n)$. Since $n$ attains large numbers (e.g. 25) according Abel-Ruffini theorem this problem isn't possible to solve analytically.



Please guide me how to find some approximation. Does iteration method a good way to solve the problem? (I mean saying iteration following: assign to $s_i$'s values, find $f(s_1,...s_n)$, therefore estimate $x$).










share|cite|improve this question











$endgroup$




Let us consider the following function: $$f(s_1,s_2,...s_n,n)=frac{1}{1+s_1}+frac{1}{(1+s_2)^2}+...+frac{1}{(1+s_n)^n},$$ where $s_iin(0,1), i=1,...,n.$
Let us introduce the following function: $$g(x,n)=frac{1}{1+x}+frac{1}{(1+x)^2}+...+frac{1}{(1+x)^n}.$$
We require that $f(s_1,s_2,...s_n,n)=g(x,n)$ and from this condition it is needed to find $x$. In other words it is needed to construct $x(s_1,...,s_n)$. Since $n$ attains large numbers (e.g. 25) according Abel-Ruffini theorem this problem isn't possible to solve analytically.



Please guide me how to find some approximation. Does iteration method a good way to solve the problem? (I mean saying iteration following: assign to $s_i$'s values, find $f(s_1,...s_n)$, therefore estimate $x$).







calculus roots






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share|cite|improve this question













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edited Dec 1 '18 at 22:04







David

















asked Dec 1 '18 at 21:28









DavidDavid

408




408












  • $begingroup$
    $g(x, n)$ is a geometric progression, isn't it?
    $endgroup$
    – user58697
    Dec 1 '18 at 23:24










  • $begingroup$
    @user58697 Yes, $g(x,n)$ is a geometric progression.
    $endgroup$
    – David
    Dec 3 '18 at 5:58


















  • $begingroup$
    $g(x, n)$ is a geometric progression, isn't it?
    $endgroup$
    – user58697
    Dec 1 '18 at 23:24










  • $begingroup$
    @user58697 Yes, $g(x,n)$ is a geometric progression.
    $endgroup$
    – David
    Dec 3 '18 at 5:58
















$begingroup$
$g(x, n)$ is a geometric progression, isn't it?
$endgroup$
– user58697
Dec 1 '18 at 23:24




$begingroup$
$g(x, n)$ is a geometric progression, isn't it?
$endgroup$
– user58697
Dec 1 '18 at 23:24












$begingroup$
@user58697 Yes, $g(x,n)$ is a geometric progression.
$endgroup$
– David
Dec 3 '18 at 5:58




$begingroup$
@user58697 Yes, $g(x,n)$ is a geometric progression.
$endgroup$
– David
Dec 3 '18 at 5:58










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