Why is a polynomial with infinite zeropoints the zeropolymomial? [duplicate]












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  • How to prove that a polynomial of degree $n$ has at most $n$ roots?

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This was given us as a fact, but why is this true? The zeropolynomial is the polynomial where all the coefficients are equal to $0$ if $R(x)$ is a polynomial over $mathbb{C}$ and every $xin mathbb{N}_0$ is a zeropoint then one can rewrite the polynomial $R(x)=x(x-1)(x-2)…(x-n)…$ but if we put an $xin mathbb{C}-mathbb{N}_0$ in $R(x)$, how does one know that $R(x)=0$?










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marked as duplicate by Dietrich Burde, Community Dec 16 '18 at 12:54


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    A polynomial of n-th degree has only n zero points.
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    – Aretino
    Dec 16 '18 at 12:40


















0












$begingroup$



This question already has an answer here:




  • How to prove that a polynomial of degree $n$ has at most $n$ roots?

    8 answers




This was given us as a fact, but why is this true? The zeropolynomial is the polynomial where all the coefficients are equal to $0$ if $R(x)$ is a polynomial over $mathbb{C}$ and every $xin mathbb{N}_0$ is a zeropoint then one can rewrite the polynomial $R(x)=x(x-1)(x-2)…(x-n)…$ but if we put an $xin mathbb{C}-mathbb{N}_0$ in $R(x)$, how does one know that $R(x)=0$?










share|cite|improve this question









$endgroup$



marked as duplicate by Dietrich Burde, Community Dec 16 '18 at 12:54


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.











  • 1




    $begingroup$
    A polynomial of n-th degree has only n zero points.
    $endgroup$
    – Aretino
    Dec 16 '18 at 12:40
















0












0








0





$begingroup$



This question already has an answer here:




  • How to prove that a polynomial of degree $n$ has at most $n$ roots?

    8 answers




This was given us as a fact, but why is this true? The zeropolynomial is the polynomial where all the coefficients are equal to $0$ if $R(x)$ is a polynomial over $mathbb{C}$ and every $xin mathbb{N}_0$ is a zeropoint then one can rewrite the polynomial $R(x)=x(x-1)(x-2)…(x-n)…$ but if we put an $xin mathbb{C}-mathbb{N}_0$ in $R(x)$, how does one know that $R(x)=0$?










share|cite|improve this question









$endgroup$





This question already has an answer here:




  • How to prove that a polynomial of degree $n$ has at most $n$ roots?

    8 answers




This was given us as a fact, but why is this true? The zeropolynomial is the polynomial where all the coefficients are equal to $0$ if $R(x)$ is a polynomial over $mathbb{C}$ and every $xin mathbb{N}_0$ is a zeropoint then one can rewrite the polynomial $R(x)=x(x-1)(x-2)…(x-n)…$ but if we put an $xin mathbb{C}-mathbb{N}_0$ in $R(x)$, how does one know that $R(x)=0$?





This question already has an answer here:




  • How to prove that a polynomial of degree $n$ has at most $n$ roots?

    8 answers








algebra-precalculus polynomials






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asked Dec 16 '18 at 12:32









RM777RM777

4029




4029




marked as duplicate by Dietrich Burde, Community Dec 16 '18 at 12:54


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.






marked as duplicate by Dietrich Burde, Community Dec 16 '18 at 12:54


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.










  • 1




    $begingroup$
    A polynomial of n-th degree has only n zero points.
    $endgroup$
    – Aretino
    Dec 16 '18 at 12:40
















  • 1




    $begingroup$
    A polynomial of n-th degree has only n zero points.
    $endgroup$
    – Aretino
    Dec 16 '18 at 12:40










1




1




$begingroup$
A polynomial of n-th degree has only n zero points.
$endgroup$
– Aretino
Dec 16 '18 at 12:40






$begingroup$
A polynomial of n-th degree has only n zero points.
$endgroup$
– Aretino
Dec 16 '18 at 12:40












2 Answers
2






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A polynomial $f(x)$ has by definition a finite degree $n$ which is given by the highest degree $n$ of the variable $x$ involved in the polynomial. If you multiply two polynomials, the degrees add (if the underlying coefficient ring has no zero divisors as in the case of a field). Only the zero polynomial has all elements (in the coefficient ring or an extension ring) as zeros. A polynomial as described cannot exist.






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    By the Fundamental theorem of algebra, a polynomial $p$ of degree $n>0$ has exactly $n$ complex roots (counting multiplicity). Let $ r_1,dots,r_n$ be its root, then we must have $p(z)ne 0$ for all $z$ such that
    $$
    |z| > max{|r_1|,dots,|r_n|} =: R
    $$

    since all the roots lie in the set ${zinBbb C: |z|le R}$.



    This means that the only polynomial with infinitely many zeroes is the consstant polynomial $pequiv0$.






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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      1












      $begingroup$

      A polynomial $f(x)$ has by definition a finite degree $n$ which is given by the highest degree $n$ of the variable $x$ involved in the polynomial. If you multiply two polynomials, the degrees add (if the underlying coefficient ring has no zero divisors as in the case of a field). Only the zero polynomial has all elements (in the coefficient ring or an extension ring) as zeros. A polynomial as described cannot exist.






      share|cite|improve this answer









      $endgroup$


















        1












        $begingroup$

        A polynomial $f(x)$ has by definition a finite degree $n$ which is given by the highest degree $n$ of the variable $x$ involved in the polynomial. If you multiply two polynomials, the degrees add (if the underlying coefficient ring has no zero divisors as in the case of a field). Only the zero polynomial has all elements (in the coefficient ring or an extension ring) as zeros. A polynomial as described cannot exist.






        share|cite|improve this answer









        $endgroup$
















          1












          1








          1





          $begingroup$

          A polynomial $f(x)$ has by definition a finite degree $n$ which is given by the highest degree $n$ of the variable $x$ involved in the polynomial. If you multiply two polynomials, the degrees add (if the underlying coefficient ring has no zero divisors as in the case of a field). Only the zero polynomial has all elements (in the coefficient ring or an extension ring) as zeros. A polynomial as described cannot exist.






          share|cite|improve this answer









          $endgroup$



          A polynomial $f(x)$ has by definition a finite degree $n$ which is given by the highest degree $n$ of the variable $x$ involved in the polynomial. If you multiply two polynomials, the degrees add (if the underlying coefficient ring has no zero divisors as in the case of a field). Only the zero polynomial has all elements (in the coefficient ring or an extension ring) as zeros. A polynomial as described cannot exist.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 16 '18 at 12:39









          WuestenfuxWuestenfux

          4,2161413




          4,2161413























              0












              $begingroup$

              By the Fundamental theorem of algebra, a polynomial $p$ of degree $n>0$ has exactly $n$ complex roots (counting multiplicity). Let $ r_1,dots,r_n$ be its root, then we must have $p(z)ne 0$ for all $z$ such that
              $$
              |z| > max{|r_1|,dots,|r_n|} =: R
              $$

              since all the roots lie in the set ${zinBbb C: |z|le R}$.



              This means that the only polynomial with infinitely many zeroes is the consstant polynomial $pequiv0$.






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                By the Fundamental theorem of algebra, a polynomial $p$ of degree $n>0$ has exactly $n$ complex roots (counting multiplicity). Let $ r_1,dots,r_n$ be its root, then we must have $p(z)ne 0$ for all $z$ such that
                $$
                |z| > max{|r_1|,dots,|r_n|} =: R
                $$

                since all the roots lie in the set ${zinBbb C: |z|le R}$.



                This means that the only polynomial with infinitely many zeroes is the consstant polynomial $pequiv0$.






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  By the Fundamental theorem of algebra, a polynomial $p$ of degree $n>0$ has exactly $n$ complex roots (counting multiplicity). Let $ r_1,dots,r_n$ be its root, then we must have $p(z)ne 0$ for all $z$ such that
                  $$
                  |z| > max{|r_1|,dots,|r_n|} =: R
                  $$

                  since all the roots lie in the set ${zinBbb C: |z|le R}$.



                  This means that the only polynomial with infinitely many zeroes is the consstant polynomial $pequiv0$.






                  share|cite|improve this answer









                  $endgroup$



                  By the Fundamental theorem of algebra, a polynomial $p$ of degree $n>0$ has exactly $n$ complex roots (counting multiplicity). Let $ r_1,dots,r_n$ be its root, then we must have $p(z)ne 0$ for all $z$ such that
                  $$
                  |z| > max{|r_1|,dots,|r_n|} =: R
                  $$

                  since all the roots lie in the set ${zinBbb C: |z|le R}$.



                  This means that the only polynomial with infinitely many zeroes is the consstant polynomial $pequiv0$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 16 '18 at 12:47









                  BigbearZzzBigbearZzz

                  8,49221652




                  8,49221652















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