Consider all linear systems with exactly one eigenvalue equal to 0. Which of these systems are conjugate?












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This question considers non-hyperbolic matrices (2x2), which is not covered in our textbook. Basically the problem I think tries to get us to think about conjugacy patterns of these cases, but I am stuck.



If A= ((a, b), (c, d)) a 2x2 has 1 eigenvalue = 0, then I believe c or b must be 0.



So A = ((a, 0), (c, d)) or ((a, b), (0, d)), but I'm not sure where to go from there.










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  • Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
    – xbh
    Oct 30 at 3:13










  • Ah yes, sorry. Shows my inexperience with linear algebra!
    – MathGuyForLife
    Oct 30 at 3:15
















0














This question considers non-hyperbolic matrices (2x2), which is not covered in our textbook. Basically the problem I think tries to get us to think about conjugacy patterns of these cases, but I am stuck.



If A= ((a, b), (c, d)) a 2x2 has 1 eigenvalue = 0, then I believe c or b must be 0.



So A = ((a, 0), (c, d)) or ((a, b), (0, d)), but I'm not sure where to go from there.










share|cite|improve this question






















  • Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
    – xbh
    Oct 30 at 3:13










  • Ah yes, sorry. Shows my inexperience with linear algebra!
    – MathGuyForLife
    Oct 30 at 3:15














0












0








0







This question considers non-hyperbolic matrices (2x2), which is not covered in our textbook. Basically the problem I think tries to get us to think about conjugacy patterns of these cases, but I am stuck.



If A= ((a, b), (c, d)) a 2x2 has 1 eigenvalue = 0, then I believe c or b must be 0.



So A = ((a, 0), (c, d)) or ((a, b), (0, d)), but I'm not sure where to go from there.










share|cite|improve this question













This question considers non-hyperbolic matrices (2x2), which is not covered in our textbook. Basically the problem I think tries to get us to think about conjugacy patterns of these cases, but I am stuck.



If A= ((a, b), (c, d)) a 2x2 has 1 eigenvalue = 0, then I believe c or b must be 0.



So A = ((a, 0), (c, d)) or ((a, b), (0, d)), but I'm not sure where to go from there.







matrices






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asked Oct 30 at 2:34









MathGuyForLife

1007




1007












  • Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
    – xbh
    Oct 30 at 3:13










  • Ah yes, sorry. Shows my inexperience with linear algebra!
    – MathGuyForLife
    Oct 30 at 3:15


















  • Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
    – xbh
    Oct 30 at 3:13










  • Ah yes, sorry. Shows my inexperience with linear algebra!
    – MathGuyForLife
    Oct 30 at 3:15
















Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
– xbh
Oct 30 at 3:13




Why did you believe this? Counterexample $$ boldsymbol A = begin{bmatrix}1&1\1&1 end{bmatrix}. $$
– xbh
Oct 30 at 3:13












Ah yes, sorry. Shows my inexperience with linear algebra!
– MathGuyForLife
Oct 30 at 3:15




Ah yes, sorry. Shows my inexperience with linear algebra!
– MathGuyForLife
Oct 30 at 3:15










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This means that the matrix has rank 1 or one row is a multiple of another row and one row is non zero. Formally$$k_1(a,b)+k_2(c,d)=0$$and $$a^2+b^2+c^2+d^2ne 0$$






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    This means that the matrix has rank 1 or one row is a multiple of another row and one row is non zero. Formally$$k_1(a,b)+k_2(c,d)=0$$and $$a^2+b^2+c^2+d^2ne 0$$






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      This means that the matrix has rank 1 or one row is a multiple of another row and one row is non zero. Formally$$k_1(a,b)+k_2(c,d)=0$$and $$a^2+b^2+c^2+d^2ne 0$$






      share|cite|improve this answer
























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        This means that the matrix has rank 1 or one row is a multiple of another row and one row is non zero. Formally$$k_1(a,b)+k_2(c,d)=0$$and $$a^2+b^2+c^2+d^2ne 0$$






        share|cite|improve this answer












        This means that the matrix has rank 1 or one row is a multiple of another row and one row is non zero. Formally$$k_1(a,b)+k_2(c,d)=0$$and $$a^2+b^2+c^2+d^2ne 0$$







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        answered Nov 24 at 18:32









        Mostafa Ayaz

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