Determine dimension of set of matrices given that each matrix has same eigenvalue 0 and eigenvector












1












$begingroup$


Let V be the set of all $A_{3×3}$ matrices, where all of them have eigenvalue 0 and corresponding eigenvector $y=(1,2,3)^T$.



Assuming we have showed that V is a vector space, determine the dimension of V.





From the definition we know that:
$x$ and $lambda$ are eigenvector and eigenvalue iff $(A-lambda I)x=0$ .



So for each matrix $A_i$ in our set$$
(A_i-0)
begin{pmatrix}
1 \
2 \
3 \
end{pmatrix}
=0
$$

$$
A_i
begin{pmatrix}
1 \
2 \
3 \
end{pmatrix}
=0
$$

$$
begin{pmatrix}
1 \
2 \
3 \
end{pmatrix}
in N(A_i)
$$

From this we find that $Nullity(A_i)geq1 Rightarrow $



$Rank(A_i) = n-Nullity(A_i)=3-1=2 Rightarrow $



$Rank(A_i)=Dim(C(A_i)) leq 2$



However, I am not sure how can I proceed from here?



1) How can determine the dimension of the matrix $A_i$ for sure?



2) How is that connected to the dimension of entire vector space formed by such matrices?










share|cite|improve this question









$endgroup$

















    1












    $begingroup$


    Let V be the set of all $A_{3×3}$ matrices, where all of them have eigenvalue 0 and corresponding eigenvector $y=(1,2,3)^T$.



    Assuming we have showed that V is a vector space, determine the dimension of V.





    From the definition we know that:
    $x$ and $lambda$ are eigenvector and eigenvalue iff $(A-lambda I)x=0$ .



    So for each matrix $A_i$ in our set$$
    (A_i-0)
    begin{pmatrix}
    1 \
    2 \
    3 \
    end{pmatrix}
    =0
    $$

    $$
    A_i
    begin{pmatrix}
    1 \
    2 \
    3 \
    end{pmatrix}
    =0
    $$

    $$
    begin{pmatrix}
    1 \
    2 \
    3 \
    end{pmatrix}
    in N(A_i)
    $$

    From this we find that $Nullity(A_i)geq1 Rightarrow $



    $Rank(A_i) = n-Nullity(A_i)=3-1=2 Rightarrow $



    $Rank(A_i)=Dim(C(A_i)) leq 2$



    However, I am not sure how can I proceed from here?



    1) How can determine the dimension of the matrix $A_i$ for sure?



    2) How is that connected to the dimension of entire vector space formed by such matrices?










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      Let V be the set of all $A_{3×3}$ matrices, where all of them have eigenvalue 0 and corresponding eigenvector $y=(1,2,3)^T$.



      Assuming we have showed that V is a vector space, determine the dimension of V.





      From the definition we know that:
      $x$ and $lambda$ are eigenvector and eigenvalue iff $(A-lambda I)x=0$ .



      So for each matrix $A_i$ in our set$$
      (A_i-0)
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      =0
      $$

      $$
      A_i
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      =0
      $$

      $$
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      in N(A_i)
      $$

      From this we find that $Nullity(A_i)geq1 Rightarrow $



      $Rank(A_i) = n-Nullity(A_i)=3-1=2 Rightarrow $



      $Rank(A_i)=Dim(C(A_i)) leq 2$



      However, I am not sure how can I proceed from here?



      1) How can determine the dimension of the matrix $A_i$ for sure?



      2) How is that connected to the dimension of entire vector space formed by such matrices?










      share|cite|improve this question









      $endgroup$




      Let V be the set of all $A_{3×3}$ matrices, where all of them have eigenvalue 0 and corresponding eigenvector $y=(1,2,3)^T$.



      Assuming we have showed that V is a vector space, determine the dimension of V.





      From the definition we know that:
      $x$ and $lambda$ are eigenvector and eigenvalue iff $(A-lambda I)x=0$ .



      So for each matrix $A_i$ in our set$$
      (A_i-0)
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      =0
      $$

      $$
      A_i
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      =0
      $$

      $$
      begin{pmatrix}
      1 \
      2 \
      3 \
      end{pmatrix}
      in N(A_i)
      $$

      From this we find that $Nullity(A_i)geq1 Rightarrow $



      $Rank(A_i) = n-Nullity(A_i)=3-1=2 Rightarrow $



      $Rank(A_i)=Dim(C(A_i)) leq 2$



      However, I am not sure how can I proceed from here?



      1) How can determine the dimension of the matrix $A_i$ for sure?



      2) How is that connected to the dimension of entire vector space formed by such matrices?







      linear-algebra vector-spaces eigenvalues-eigenvectors






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 15 at 19:38









      Jill WhiteJill White

      133




      133






















          0






          active

          oldest

          votes











          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "69"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3074858%2fdetermine-dimension-of-set-of-matrices-given-that-each-matrix-has-same-eigenvalu%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          0






          active

          oldest

          votes








          0






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes
















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Mathematics Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3074858%2fdetermine-dimension-of-set-of-matrices-given-that-each-matrix-has-same-eigenvalu%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          'app-layout' is not a known element: how to share Component with different Modules

          android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

          SQL update select statement