Show that R (reflection operator) is diagonalizable.












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Let be $V$ a real vector space (finite dimension) with standard scalar product, $S$ an $V-$subspace and $R: Vrightarrow V$ the reflection operator on $S$. Show that $R$ is a diagonalizable operator.



I can think of how to do it on the plane - using eigenvalues and eigenvectors. But this question, I honestly do not know how to begin.










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    1












    $begingroup$


    Let be $V$ a real vector space (finite dimension) with standard scalar product, $S$ an $V-$subspace and $R: Vrightarrow V$ the reflection operator on $S$. Show that $R$ is a diagonalizable operator.



    I can think of how to do it on the plane - using eigenvalues and eigenvectors. But this question, I honestly do not know how to begin.










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      Let be $V$ a real vector space (finite dimension) with standard scalar product, $S$ an $V-$subspace and $R: Vrightarrow V$ the reflection operator on $S$. Show that $R$ is a diagonalizable operator.



      I can think of how to do it on the plane - using eigenvalues and eigenvectors. But this question, I honestly do not know how to begin.










      share|cite|improve this question











      $endgroup$




      Let be $V$ a real vector space (finite dimension) with standard scalar product, $S$ an $V-$subspace and $R: Vrightarrow V$ the reflection operator on $S$. Show that $R$ is a diagonalizable operator.



      I can think of how to do it on the plane - using eigenvalues and eigenvectors. But this question, I honestly do not know how to begin.







      linear-algebra linear-transformations euclidean-geometry diagonalization






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      share|cite|improve this question













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      share|cite|improve this question








      edited Dec 2 '18 at 18:34









      Servaes

      22.5k33793




      22.5k33793










      asked Dec 2 '18 at 18:26









      Juliana de SouzaJuliana de Souza

      656




      656






















          2 Answers
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          $begingroup$

          HINT: Decompose $V$ as $Soplus S^{perp}$. What do $Rvert_S$ and $Rvert_{S^{perp}}$ look like?






          share|cite|improve this answer









          $endgroup$









          • 1




            $begingroup$
            Very good hint.
            $endgroup$
            – rschwieb
            Dec 2 '18 at 18:33



















          1












          $begingroup$

          Since A is reflection operator so it will satisfy the equation $A^2=I$. So it can be easily seen that the minimal polynomial of A will annihilate the polynomial $(x^2-1)$ so minimal polynomial of A is either (x-1) or (x+1) or (x-1)(x+1). In each case minimal polynomial have only linear factors. Therefore the operator A is diagnolisable.






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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            3












            $begingroup$

            HINT: Decompose $V$ as $Soplus S^{perp}$. What do $Rvert_S$ and $Rvert_{S^{perp}}$ look like?






            share|cite|improve this answer









            $endgroup$









            • 1




              $begingroup$
              Very good hint.
              $endgroup$
              – rschwieb
              Dec 2 '18 at 18:33
















            3












            $begingroup$

            HINT: Decompose $V$ as $Soplus S^{perp}$. What do $Rvert_S$ and $Rvert_{S^{perp}}$ look like?






            share|cite|improve this answer









            $endgroup$









            • 1




              $begingroup$
              Very good hint.
              $endgroup$
              – rschwieb
              Dec 2 '18 at 18:33














            3












            3








            3





            $begingroup$

            HINT: Decompose $V$ as $Soplus S^{perp}$. What do $Rvert_S$ and $Rvert_{S^{perp}}$ look like?






            share|cite|improve this answer









            $endgroup$



            HINT: Decompose $V$ as $Soplus S^{perp}$. What do $Rvert_S$ and $Rvert_{S^{perp}}$ look like?







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Dec 2 '18 at 18:30









            ServaesServaes

            22.5k33793




            22.5k33793








            • 1




              $begingroup$
              Very good hint.
              $endgroup$
              – rschwieb
              Dec 2 '18 at 18:33














            • 1




              $begingroup$
              Very good hint.
              $endgroup$
              – rschwieb
              Dec 2 '18 at 18:33








            1




            1




            $begingroup$
            Very good hint.
            $endgroup$
            – rschwieb
            Dec 2 '18 at 18:33




            $begingroup$
            Very good hint.
            $endgroup$
            – rschwieb
            Dec 2 '18 at 18:33











            1












            $begingroup$

            Since A is reflection operator so it will satisfy the equation $A^2=I$. So it can be easily seen that the minimal polynomial of A will annihilate the polynomial $(x^2-1)$ so minimal polynomial of A is either (x-1) or (x+1) or (x-1)(x+1). In each case minimal polynomial have only linear factors. Therefore the operator A is diagnolisable.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              Since A is reflection operator so it will satisfy the equation $A^2=I$. So it can be easily seen that the minimal polynomial of A will annihilate the polynomial $(x^2-1)$ so minimal polynomial of A is either (x-1) or (x+1) or (x-1)(x+1). In each case minimal polynomial have only linear factors. Therefore the operator A is diagnolisable.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                Since A is reflection operator so it will satisfy the equation $A^2=I$. So it can be easily seen that the minimal polynomial of A will annihilate the polynomial $(x^2-1)$ so minimal polynomial of A is either (x-1) or (x+1) or (x-1)(x+1). In each case minimal polynomial have only linear factors. Therefore the operator A is diagnolisable.






                share|cite|improve this answer









                $endgroup$



                Since A is reflection operator so it will satisfy the equation $A^2=I$. So it can be easily seen that the minimal polynomial of A will annihilate the polynomial $(x^2-1)$ so minimal polynomial of A is either (x-1) or (x+1) or (x-1)(x+1). In each case minimal polynomial have only linear factors. Therefore the operator A is diagnolisable.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 2 '18 at 18:47









                MANI SHANKAR PANDEYMANI SHANKAR PANDEY

                477




                477






























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