A question about vector space, sub-spaces and linear transformation












1












$begingroup$


I have a homework question that I don't know how to start:



let $V$ be a vector space under field $F$, $dim(V) = n$.



let $T: V to V$ be a linear transformation.



prove if $U subseteq V$, and $dim(U) = k$, such that for every $u in U$, $T(u) in U$, then there exists a basis $B$ of $V$ such that:



$[T]^B_B =$
$
begin{bmatrix}
A_1 & A_3 \
0 & A_2 \
end{bmatrix}
$



So that $A_3 ∈ M_{k×(n−k)}(F)$, $A_2 in M_{(n−k)×(n−k)}(F)$ and $A_1 in M_{k×k}(F)$



Thank you for your help!










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Please use MathJax to format your post so it's easier to read.
    $endgroup$
    – saulspatz
    Jan 2 at 20:17






  • 1




    $begingroup$
    I edited it, it just took me some time.
    $endgroup$
    – assaf
    Jan 2 at 20:27
















1












$begingroup$


I have a homework question that I don't know how to start:



let $V$ be a vector space under field $F$, $dim(V) = n$.



let $T: V to V$ be a linear transformation.



prove if $U subseteq V$, and $dim(U) = k$, such that for every $u in U$, $T(u) in U$, then there exists a basis $B$ of $V$ such that:



$[T]^B_B =$
$
begin{bmatrix}
A_1 & A_3 \
0 & A_2 \
end{bmatrix}
$



So that $A_3 ∈ M_{k×(n−k)}(F)$, $A_2 in M_{(n−k)×(n−k)}(F)$ and $A_1 in M_{k×k}(F)$



Thank you for your help!










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Please use MathJax to format your post so it's easier to read.
    $endgroup$
    – saulspatz
    Jan 2 at 20:17






  • 1




    $begingroup$
    I edited it, it just took me some time.
    $endgroup$
    – assaf
    Jan 2 at 20:27














1












1








1





$begingroup$


I have a homework question that I don't know how to start:



let $V$ be a vector space under field $F$, $dim(V) = n$.



let $T: V to V$ be a linear transformation.



prove if $U subseteq V$, and $dim(U) = k$, such that for every $u in U$, $T(u) in U$, then there exists a basis $B$ of $V$ such that:



$[T]^B_B =$
$
begin{bmatrix}
A_1 & A_3 \
0 & A_2 \
end{bmatrix}
$



So that $A_3 ∈ M_{k×(n−k)}(F)$, $A_2 in M_{(n−k)×(n−k)}(F)$ and $A_1 in M_{k×k}(F)$



Thank you for your help!










share|cite|improve this question











$endgroup$




I have a homework question that I don't know how to start:



let $V$ be a vector space under field $F$, $dim(V) = n$.



let $T: V to V$ be a linear transformation.



prove if $U subseteq V$, and $dim(U) = k$, such that for every $u in U$, $T(u) in U$, then there exists a basis $B$ of $V$ such that:



$[T]^B_B =$
$
begin{bmatrix}
A_1 & A_3 \
0 & A_2 \
end{bmatrix}
$



So that $A_3 ∈ M_{k×(n−k)}(F)$, $A_2 in M_{(n−k)×(n−k)}(F)$ and $A_1 in M_{k×k}(F)$



Thank you for your help!







linear-algebra matrices vector-spaces linear-transformations






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 2 at 21:33









A.Γ.

22.7k32656




22.7k32656










asked Jan 2 at 20:09









assafassaf

133




133








  • 1




    $begingroup$
    Please use MathJax to format your post so it's easier to read.
    $endgroup$
    – saulspatz
    Jan 2 at 20:17






  • 1




    $begingroup$
    I edited it, it just took me some time.
    $endgroup$
    – assaf
    Jan 2 at 20:27














  • 1




    $begingroup$
    Please use MathJax to format your post so it's easier to read.
    $endgroup$
    – saulspatz
    Jan 2 at 20:17






  • 1




    $begingroup$
    I edited it, it just took me some time.
    $endgroup$
    – assaf
    Jan 2 at 20:27








1




1




$begingroup$
Please use MathJax to format your post so it's easier to read.
$endgroup$
– saulspatz
Jan 2 at 20:17




$begingroup$
Please use MathJax to format your post so it's easier to read.
$endgroup$
– saulspatz
Jan 2 at 20:17




1




1




$begingroup$
I edited it, it just took me some time.
$endgroup$
– assaf
Jan 2 at 20:27




$begingroup$
I edited it, it just took me some time.
$endgroup$
– assaf
Jan 2 at 20:27










3 Answers
3






active

oldest

votes


















0












$begingroup$

Hint: Take a basis $u_1,dots,u_k$ of $U$ and complete it to a basis $u_1,dots,u_k,u_{k+1},dots,u_n$ of $V$.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    Hint: try to construct the basis $B$. Start with a basis of $U$ ($k$ vectors) and complete it to a basis in $V$ by $n-k$ linearly independent vectors. How does the matrix of $T$ look like in this basis?






    share|cite|improve this answer









    $endgroup$





















      0












      $begingroup$

      First you argue that there is a basis of $V$ such that any element of $U$ can be written as $(u_1,dots,u_k,0,dots,0)in V$.



      Using this and that by assumption $T(U)subset U$ we deduce that the matrix representation of $T$ in this basis will be:
      $$
      begin{bmatrix}
      A & B \
      C & D \
      end{bmatrix}
      $$

      where $A$ is a $ktimes k$ matrix and $C=0$.






      share|cite|improve this answer









      $endgroup$













        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%2f3059918%2fa-question-about-vector-space-sub-spaces-and-linear-transformation%23new-answer', 'question_page');
        }
        );

        Post as a guest















        Required, but never shown

























        3 Answers
        3






        active

        oldest

        votes








        3 Answers
        3






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes









        0












        $begingroup$

        Hint: Take a basis $u_1,dots,u_k$ of $U$ and complete it to a basis $u_1,dots,u_k,u_{k+1},dots,u_n$ of $V$.






        share|cite|improve this answer









        $endgroup$


















          0












          $begingroup$

          Hint: Take a basis $u_1,dots,u_k$ of $U$ and complete it to a basis $u_1,dots,u_k,u_{k+1},dots,u_n$ of $V$.






          share|cite|improve this answer









          $endgroup$
















            0












            0








            0





            $begingroup$

            Hint: Take a basis $u_1,dots,u_k$ of $U$ and complete it to a basis $u_1,dots,u_k,u_{k+1},dots,u_n$ of $V$.






            share|cite|improve this answer









            $endgroup$



            Hint: Take a basis $u_1,dots,u_k$ of $U$ and complete it to a basis $u_1,dots,u_k,u_{k+1},dots,u_n$ of $V$.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Jan 2 at 21:31









            ScientificaScientifica

            6,37641335




            6,37641335























                0












                $begingroup$

                Hint: try to construct the basis $B$. Start with a basis of $U$ ($k$ vectors) and complete it to a basis in $V$ by $n-k$ linearly independent vectors. How does the matrix of $T$ look like in this basis?






                share|cite|improve this answer









                $endgroup$


















                  0












                  $begingroup$

                  Hint: try to construct the basis $B$. Start with a basis of $U$ ($k$ vectors) and complete it to a basis in $V$ by $n-k$ linearly independent vectors. How does the matrix of $T$ look like in this basis?






                  share|cite|improve this answer









                  $endgroup$
















                    0












                    0








                    0





                    $begingroup$

                    Hint: try to construct the basis $B$. Start with a basis of $U$ ($k$ vectors) and complete it to a basis in $V$ by $n-k$ linearly independent vectors. How does the matrix of $T$ look like in this basis?






                    share|cite|improve this answer









                    $endgroup$



                    Hint: try to construct the basis $B$. Start with a basis of $U$ ($k$ vectors) and complete it to a basis in $V$ by $n-k$ linearly independent vectors. How does the matrix of $T$ look like in this basis?







                    share|cite|improve this answer












                    share|cite|improve this answer



                    share|cite|improve this answer










                    answered Jan 2 at 21:31









                    A.Γ.A.Γ.

                    22.7k32656




                    22.7k32656























                        0












                        $begingroup$

                        First you argue that there is a basis of $V$ such that any element of $U$ can be written as $(u_1,dots,u_k,0,dots,0)in V$.



                        Using this and that by assumption $T(U)subset U$ we deduce that the matrix representation of $T$ in this basis will be:
                        $$
                        begin{bmatrix}
                        A & B \
                        C & D \
                        end{bmatrix}
                        $$

                        where $A$ is a $ktimes k$ matrix and $C=0$.






                        share|cite|improve this answer









                        $endgroup$


















                          0












                          $begingroup$

                          First you argue that there is a basis of $V$ such that any element of $U$ can be written as $(u_1,dots,u_k,0,dots,0)in V$.



                          Using this and that by assumption $T(U)subset U$ we deduce that the matrix representation of $T$ in this basis will be:
                          $$
                          begin{bmatrix}
                          A & B \
                          C & D \
                          end{bmatrix}
                          $$

                          where $A$ is a $ktimes k$ matrix and $C=0$.






                          share|cite|improve this answer









                          $endgroup$
















                            0












                            0








                            0





                            $begingroup$

                            First you argue that there is a basis of $V$ such that any element of $U$ can be written as $(u_1,dots,u_k,0,dots,0)in V$.



                            Using this and that by assumption $T(U)subset U$ we deduce that the matrix representation of $T$ in this basis will be:
                            $$
                            begin{bmatrix}
                            A & B \
                            C & D \
                            end{bmatrix}
                            $$

                            where $A$ is a $ktimes k$ matrix and $C=0$.






                            share|cite|improve this answer









                            $endgroup$



                            First you argue that there is a basis of $V$ such that any element of $U$ can be written as $(u_1,dots,u_k,0,dots,0)in V$.



                            Using this and that by assumption $T(U)subset U$ we deduce that the matrix representation of $T$ in this basis will be:
                            $$
                            begin{bmatrix}
                            A & B \
                            C & D \
                            end{bmatrix}
                            $$

                            where $A$ is a $ktimes k$ matrix and $C=0$.







                            share|cite|improve this answer












                            share|cite|improve this answer



                            share|cite|improve this answer










                            answered Jan 2 at 21:46









                            Test123Test123

                            2,762828




                            2,762828






























                                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%2f3059918%2fa-question-about-vector-space-sub-spaces-and-linear-transformation%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

                                MongoDB - Not Authorized To Execute Command

                                How to fix TextFormField cause rebuild widget in Flutter

                                in spring boot 2.1 many test slices are not allowed anymore due to multiple @BootstrapWith