Every operator $Tin mathcal L(V)$ where $V$ is a $mathbb C-$vector space has an eigenvalue.

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
0
down vote

favorite












Let $V$ a $mathbb C-$vector space of finite dimension (let say $n$) and $Tin mathcal L(V)$. Then $T$ has at least one eigenvalue.



I don't understand the proof.



The list $(v,T(v),...,T^n(v))$ is linearly dependent, i.e. there is $alpha _i$ not all zero s.t. $$alpha _0v+alpha _1T+...+alpha _nT^n(v)=0$$
for all $v$. Let $alpha _mneq 0$ the biggest one i.e. $alpha _k=0$ for all $k>m$. Then $$0=alpha _0v+...+alpha _mT^m(v)=c(T-lambda _1I)...(T-lambda _mI)v,$$
and thus there is $j$ s.t. $T-lambda _jI$ is not injective.



Question : I don't understand why there is $j$ s.t. $T-lambda _jI$ is not injective.







share|cite|improve this question























    up vote
    0
    down vote

    favorite












    Let $V$ a $mathbb C-$vector space of finite dimension (let say $n$) and $Tin mathcal L(V)$. Then $T$ has at least one eigenvalue.



    I don't understand the proof.



    The list $(v,T(v),...,T^n(v))$ is linearly dependent, i.e. there is $alpha _i$ not all zero s.t. $$alpha _0v+alpha _1T+...+alpha _nT^n(v)=0$$
    for all $v$. Let $alpha _mneq 0$ the biggest one i.e. $alpha _k=0$ for all $k>m$. Then $$0=alpha _0v+...+alpha _mT^m(v)=c(T-lambda _1I)...(T-lambda _mI)v,$$
    and thus there is $j$ s.t. $T-lambda _jI$ is not injective.



    Question : I don't understand why there is $j$ s.t. $T-lambda _jI$ is not injective.







    share|cite|improve this question





















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Let $V$ a $mathbb C-$vector space of finite dimension (let say $n$) and $Tin mathcal L(V)$. Then $T$ has at least one eigenvalue.



      I don't understand the proof.



      The list $(v,T(v),...,T^n(v))$ is linearly dependent, i.e. there is $alpha _i$ not all zero s.t. $$alpha _0v+alpha _1T+...+alpha _nT^n(v)=0$$
      for all $v$. Let $alpha _mneq 0$ the biggest one i.e. $alpha _k=0$ for all $k>m$. Then $$0=alpha _0v+...+alpha _mT^m(v)=c(T-lambda _1I)...(T-lambda _mI)v,$$
      and thus there is $j$ s.t. $T-lambda _jI$ is not injective.



      Question : I don't understand why there is $j$ s.t. $T-lambda _jI$ is not injective.







      share|cite|improve this question











      Let $V$ a $mathbb C-$vector space of finite dimension (let say $n$) and $Tin mathcal L(V)$. Then $T$ has at least one eigenvalue.



      I don't understand the proof.



      The list $(v,T(v),...,T^n(v))$ is linearly dependent, i.e. there is $alpha _i$ not all zero s.t. $$alpha _0v+alpha _1T+...+alpha _nT^n(v)=0$$
      for all $v$. Let $alpha _mneq 0$ the biggest one i.e. $alpha _k=0$ for all $k>m$. Then $$0=alpha _0v+...+alpha _mT^m(v)=c(T-lambda _1I)...(T-lambda _mI)v,$$
      and thus there is $j$ s.t. $T-lambda _jI$ is not injective.



      Question : I don't understand why there is $j$ s.t. $T-lambda _jI$ is not injective.









      share|cite|improve this question










      share|cite|improve this question




      share|cite|improve this question









      asked Aug 6 at 8:48









      Henri

      404




      404




















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          2
          down vote



          accepted










          Product of a finite number of injective linear maps is injective. Since $0$ is not injective it follows that one of the factors on the right is not injective.






          share|cite|improve this answer





















            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',
            convertImagesToLinks: true,
            noModals: false,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            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%2f2873706%2fevery-operator-t-in-mathcal-lv-where-v-is-a-mathbb-c-vector-space-has%23new-answer', 'question_page');

            );

            Post as a guest






























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            2
            down vote



            accepted










            Product of a finite number of injective linear maps is injective. Since $0$ is not injective it follows that one of the factors on the right is not injective.






            share|cite|improve this answer

























              up vote
              2
              down vote



              accepted










              Product of a finite number of injective linear maps is injective. Since $0$ is not injective it follows that one of the factors on the right is not injective.






              share|cite|improve this answer























                up vote
                2
                down vote



                accepted







                up vote
                2
                down vote



                accepted






                Product of a finite number of injective linear maps is injective. Since $0$ is not injective it follows that one of the factors on the right is not injective.






                share|cite|improve this answer













                Product of a finite number of injective linear maps is injective. Since $0$ is not injective it follows that one of the factors on the right is not injective.







                share|cite|improve this answer













                share|cite|improve this answer



                share|cite|improve this answer











                answered Aug 6 at 8:51









                Kavi Rama Murthy

                21k2830




                21k2830






















                     

                    draft saved


                    draft discarded


























                     


                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function ()
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2873706%2fevery-operator-t-in-mathcal-lv-where-v-is-a-mathbb-c-vector-space-has%23new-answer', 'question_page');

                    );

                    Post as a guest













































































                    Comments

                    Popular posts from this blog

                    What is the equation of a 3D cone with generalised tilt?

                    Color the edges and diagonals of a regular polygon

                    Relationship between determinant of matrix and determinant of adjoint?