show that $I, T, T^2, …, T^k$ are linear dependent












0












$begingroup$


I am learning linear algebra and new to it. I can not solve this problem. I think it has a trick that I don't know.




for T(a linear map), $T:Vrightarrow V$ and every $v$ in $V$ the $v, T(v), T^2(v), ..., T^k(v)$ are linearly dependent where $k$ is a natural number $leq dim(V)$.



show that $I, T, T^2, ..., T^k$ are linearly dependent




thanks in advance.










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is T? A matrix?
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:36










  • $begingroup$
    @H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:47












  • $begingroup$
    Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:49










  • $begingroup$
    @H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:57






  • 1




    $begingroup$
    If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
    $endgroup$
    – Will M.
    Dec 24 '18 at 7:55


















0












$begingroup$


I am learning linear algebra and new to it. I can not solve this problem. I think it has a trick that I don't know.




for T(a linear map), $T:Vrightarrow V$ and every $v$ in $V$ the $v, T(v), T^2(v), ..., T^k(v)$ are linearly dependent where $k$ is a natural number $leq dim(V)$.



show that $I, T, T^2, ..., T^k$ are linearly dependent




thanks in advance.










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is T? A matrix?
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:36










  • $begingroup$
    @H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:47












  • $begingroup$
    Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:49










  • $begingroup$
    @H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:57






  • 1




    $begingroup$
    If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
    $endgroup$
    – Will M.
    Dec 24 '18 at 7:55
















0












0








0





$begingroup$


I am learning linear algebra and new to it. I can not solve this problem. I think it has a trick that I don't know.




for T(a linear map), $T:Vrightarrow V$ and every $v$ in $V$ the $v, T(v), T^2(v), ..., T^k(v)$ are linearly dependent where $k$ is a natural number $leq dim(V)$.



show that $I, T, T^2, ..., T^k$ are linearly dependent




thanks in advance.










share|cite|improve this question











$endgroup$




I am learning linear algebra and new to it. I can not solve this problem. I think it has a trick that I don't know.




for T(a linear map), $T:Vrightarrow V$ and every $v$ in $V$ the $v, T(v), T^2(v), ..., T^k(v)$ are linearly dependent where $k$ is a natural number $leq dim(V)$.



show that $I, T, T^2, ..., T^k$ are linearly dependent




thanks in advance.







linear-algebra matrices linear-transformations independence






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 15 at 12:04







Peyman mohseni kiasari

















asked Dec 20 '18 at 22:08









Peyman mohseni kiasariPeyman mohseni kiasari

1089




1089












  • $begingroup$
    What is T? A matrix?
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:36










  • $begingroup$
    @H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:47












  • $begingroup$
    Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:49










  • $begingroup$
    @H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:57






  • 1




    $begingroup$
    If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
    $endgroup$
    – Will M.
    Dec 24 '18 at 7:55




















  • $begingroup$
    What is T? A matrix?
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:36










  • $begingroup$
    @H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:47












  • $begingroup$
    Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
    $endgroup$
    – H_1317
    Dec 23 '18 at 23:49










  • $begingroup$
    @H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
    $endgroup$
    – Peyman mohseni kiasari
    Dec 23 '18 at 23:57






  • 1




    $begingroup$
    If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
    $endgroup$
    – Will M.
    Dec 24 '18 at 7:55


















$begingroup$
What is T? A matrix?
$endgroup$
– H_1317
Dec 23 '18 at 23:36




$begingroup$
What is T? A matrix?
$endgroup$
– H_1317
Dec 23 '18 at 23:36












$begingroup$
@H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 23:47






$begingroup$
@H_1317 yes, T is actually "T:V→V". unfortunately, I've asked the question wrong! it must be actually "T(v)s are dependent prove Ts are dependent". I mean both "independent"s should be "dependent". when I saw guys were answering the question I didn't edit that and just accept the answer.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 23:47














$begingroup$
Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
$endgroup$
– H_1317
Dec 23 '18 at 23:49




$begingroup$
Can u edit your question identifying what T is, and the proper wording for any other errors please? Also what vector space u believe T is in (a matrix space?) thanks
$endgroup$
– H_1317
Dec 23 '18 at 23:49












$begingroup$
@H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 23:57




$begingroup$
@H_1317, sorry if I'm not so familiar but I think "T:V→V" is a linear map no? where T must be a matrix, am I wrong? T is a map from V to V where V can be any vector space I think.
$endgroup$
– Peyman mohseni kiasari
Dec 23 '18 at 23:57




1




1




$begingroup$
If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
$endgroup$
– Will M.
Dec 24 '18 at 7:55






$begingroup$
If $a_i T^i = 0$ is a linear combination of the $T^i,$ choose some $v$ for which the $T^i(v)$ are linearly independent vectors (you need to assume that only one such $v$ exists, not that every $v$ (which, by the way cannot be) satisfies it) and then conclude all scalars are zero.
$endgroup$
– Will M.
Dec 24 '18 at 7:55












2 Answers
2






active

oldest

votes


















4












$begingroup$

Suppose $a_1T+...+a_kT^k=0$. Let $xneq 0$, $a_1T(x)+...+a_kT^k(x)=0$, this implies that $a_1=..=a_k=0$ since $T(x),...T^k(x)$ are linearly independent. It results that $T,....T^k$ is linearly independent.



Remark, you have to suppose for every $vneq 0$, $T(v),...,T^k(v)$ is linearly independent since it is not true for $v=0$.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    Hint :



    Suppose that $T,T^2,dots, T^k$ are not linearly independent. Then, there exists $lambda_1, lambda_2, dots, lambda_k in mathbb R$ not all zero, such that :



    $$lambda_1T + lambda_2T^2 + cdots + lambda_kT^k = 0$$






    share|cite|improve this answer











    $endgroup$













    • $begingroup$
      such that what!?
      $endgroup$
      – Peyman mohseni kiasari
      Dec 20 '18 at 22:13










    • $begingroup$
      @Peyman Fixed. Thanks.
      $endgroup$
      – Rebellos
      Dec 20 '18 at 22:14











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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

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    4












    $begingroup$

    Suppose $a_1T+...+a_kT^k=0$. Let $xneq 0$, $a_1T(x)+...+a_kT^k(x)=0$, this implies that $a_1=..=a_k=0$ since $T(x),...T^k(x)$ are linearly independent. It results that $T,....T^k$ is linearly independent.



    Remark, you have to suppose for every $vneq 0$, $T(v),...,T^k(v)$ is linearly independent since it is not true for $v=0$.






    share|cite|improve this answer









    $endgroup$


















      4












      $begingroup$

      Suppose $a_1T+...+a_kT^k=0$. Let $xneq 0$, $a_1T(x)+...+a_kT^k(x)=0$, this implies that $a_1=..=a_k=0$ since $T(x),...T^k(x)$ are linearly independent. It results that $T,....T^k$ is linearly independent.



      Remark, you have to suppose for every $vneq 0$, $T(v),...,T^k(v)$ is linearly independent since it is not true for $v=0$.






      share|cite|improve this answer









      $endgroup$
















        4












        4








        4





        $begingroup$

        Suppose $a_1T+...+a_kT^k=0$. Let $xneq 0$, $a_1T(x)+...+a_kT^k(x)=0$, this implies that $a_1=..=a_k=0$ since $T(x),...T^k(x)$ are linearly independent. It results that $T,....T^k$ is linearly independent.



        Remark, you have to suppose for every $vneq 0$, $T(v),...,T^k(v)$ is linearly independent since it is not true for $v=0$.






        share|cite|improve this answer









        $endgroup$



        Suppose $a_1T+...+a_kT^k=0$. Let $xneq 0$, $a_1T(x)+...+a_kT^k(x)=0$, this implies that $a_1=..=a_k=0$ since $T(x),...T^k(x)$ are linearly independent. It results that $T,....T^k$ is linearly independent.



        Remark, you have to suppose for every $vneq 0$, $T(v),...,T^k(v)$ is linearly independent since it is not true for $v=0$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 20 '18 at 22:12









        Tsemo AristideTsemo Aristide

        58.3k11445




        58.3k11445























            0












            $begingroup$

            Hint :



            Suppose that $T,T^2,dots, T^k$ are not linearly independent. Then, there exists $lambda_1, lambda_2, dots, lambda_k in mathbb R$ not all zero, such that :



            $$lambda_1T + lambda_2T^2 + cdots + lambda_kT^k = 0$$






            share|cite|improve this answer











            $endgroup$













            • $begingroup$
              such that what!?
              $endgroup$
              – Peyman mohseni kiasari
              Dec 20 '18 at 22:13










            • $begingroup$
              @Peyman Fixed. Thanks.
              $endgroup$
              – Rebellos
              Dec 20 '18 at 22:14
















            0












            $begingroup$

            Hint :



            Suppose that $T,T^2,dots, T^k$ are not linearly independent. Then, there exists $lambda_1, lambda_2, dots, lambda_k in mathbb R$ not all zero, such that :



            $$lambda_1T + lambda_2T^2 + cdots + lambda_kT^k = 0$$






            share|cite|improve this answer











            $endgroup$













            • $begingroup$
              such that what!?
              $endgroup$
              – Peyman mohseni kiasari
              Dec 20 '18 at 22:13










            • $begingroup$
              @Peyman Fixed. Thanks.
              $endgroup$
              – Rebellos
              Dec 20 '18 at 22:14














            0












            0








            0





            $begingroup$

            Hint :



            Suppose that $T,T^2,dots, T^k$ are not linearly independent. Then, there exists $lambda_1, lambda_2, dots, lambda_k in mathbb R$ not all zero, such that :



            $$lambda_1T + lambda_2T^2 + cdots + lambda_kT^k = 0$$






            share|cite|improve this answer











            $endgroup$



            Hint :



            Suppose that $T,T^2,dots, T^k$ are not linearly independent. Then, there exists $lambda_1, lambda_2, dots, lambda_k in mathbb R$ not all zero, such that :



            $$lambda_1T + lambda_2T^2 + cdots + lambda_kT^k = 0$$







            share|cite|improve this answer














            share|cite|improve this answer



            share|cite|improve this answer








            edited Dec 20 '18 at 22:13

























            answered Dec 20 '18 at 22:13









            RebellosRebellos

            14.8k31248




            14.8k31248












            • $begingroup$
              such that what!?
              $endgroup$
              – Peyman mohseni kiasari
              Dec 20 '18 at 22:13










            • $begingroup$
              @Peyman Fixed. Thanks.
              $endgroup$
              – Rebellos
              Dec 20 '18 at 22:14


















            • $begingroup$
              such that what!?
              $endgroup$
              – Peyman mohseni kiasari
              Dec 20 '18 at 22:13










            • $begingroup$
              @Peyman Fixed. Thanks.
              $endgroup$
              – Rebellos
              Dec 20 '18 at 22:14
















            $begingroup$
            such that what!?
            $endgroup$
            – Peyman mohseni kiasari
            Dec 20 '18 at 22:13




            $begingroup$
            such that what!?
            $endgroup$
            – Peyman mohseni kiasari
            Dec 20 '18 at 22:13












            $begingroup$
            @Peyman Fixed. Thanks.
            $endgroup$
            – Rebellos
            Dec 20 '18 at 22:14




            $begingroup$
            @Peyman Fixed. Thanks.
            $endgroup$
            – Rebellos
            Dec 20 '18 at 22:14


















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