linear algebra - spaces and subspaces












0












$begingroup$


Let $U ne {0}$ be a sub-space of a finite-dimensional vector space $V$. Assume that there exists a unique subspace $W subset V$, such that $V = U oplus W$. Prove that $U = V$.



I don't know how to start. please give me some guidelines...










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
    $endgroup$
    – Trevor Gunn
    Jan 28 at 16:14
















0












$begingroup$


Let $U ne {0}$ be a sub-space of a finite-dimensional vector space $V$. Assume that there exists a unique subspace $W subset V$, such that $V = U oplus W$. Prove that $U = V$.



I don't know how to start. please give me some guidelines...










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
    $endgroup$
    – Trevor Gunn
    Jan 28 at 16:14














0












0








0





$begingroup$


Let $U ne {0}$ be a sub-space of a finite-dimensional vector space $V$. Assume that there exists a unique subspace $W subset V$, such that $V = U oplus W$. Prove that $U = V$.



I don't know how to start. please give me some guidelines...










share|cite|improve this question











$endgroup$




Let $U ne {0}$ be a sub-space of a finite-dimensional vector space $V$. Assume that there exists a unique subspace $W subset V$, such that $V = U oplus W$. Prove that $U = V$.



I don't know how to start. please give me some guidelines...







linear-algebra vector-spaces






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 28 at 16:12









gt6989b

35.2k22557




35.2k22557










asked Jan 28 at 16:07









user3523226user3523226

357




357








  • 1




    $begingroup$
    Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
    $endgroup$
    – Trevor Gunn
    Jan 28 at 16:14














  • 1




    $begingroup$
    Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
    $endgroup$
    – Trevor Gunn
    Jan 28 at 16:14








1




1




$begingroup$
Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
$endgroup$
– Trevor Gunn
Jan 28 at 16:14




$begingroup$
Please do not ask questions that consist only of a problem statement and "I don't know how to start." These don't make good questions and they aren't a good fit for this site. See the advice here.
$endgroup$
– Trevor Gunn
Jan 28 at 16:14










1 Answer
1






active

oldest

votes


















1












$begingroup$

HINT



Prove that $W$ is also a subspace of $V$, then by uniqueness of $U$, it must be that $W = U$ or $W = {0}$.






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%2f3091057%2flinear-algebra-spaces-and-subspaces%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    1












    $begingroup$

    HINT



    Prove that $W$ is also a subspace of $V$, then by uniqueness of $U$, it must be that $W = U$ or $W = {0}$.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      HINT



      Prove that $W$ is also a subspace of $V$, then by uniqueness of $U$, it must be that $W = U$ or $W = {0}$.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        HINT



        Prove that $W$ is also a subspace of $V$, then by uniqueness of $U$, it must be that $W = U$ or $W = {0}$.






        share|cite|improve this answer









        $endgroup$



        HINT



        Prove that $W$ is also a subspace of $V$, then by uniqueness of $U$, it must be that $W = U$ or $W = {0}$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 28 at 16:15









        gt6989bgt6989b

        35.2k22557




        35.2k22557






























            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%2f3091057%2flinear-algebra-spaces-and-subspaces%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

            Npm cannot find a required file even through it is in the searched directory