Help with this matrix problem











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Let $A in mathbb{Q}^{mtimes n}$. Proof that if A has at least two distinct right-inverses, then A has infinitely many right-inverses.



I began this proof as follows:



Let suppose that $B,C in K^{ntimes m}$ are two distinct right-inverses for $A$. Then, $AB=I_{n}$ and $AC=I_{n}$. Then we have $AB+AC=2I_{n} iff A(dfrac{1}{2}(B+C))=I_{n}$.



Then $dfrac{1}{2}(B+C) in K^{m times n}$ is also a right-inverse for $A$. I think repeating this process I could prove the proposition, but I'm not really sure. Is there another way? (without Gauss-Jordan algorithm)










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  • 1




    If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
    – copper.hat
    Nov 17 at 5:10










  • Thanks a lot !
    – Abraham Hernández
    Nov 17 at 5:18















up vote
-1
down vote

favorite












Let $A in mathbb{Q}^{mtimes n}$. Proof that if A has at least two distinct right-inverses, then A has infinitely many right-inverses.



I began this proof as follows:



Let suppose that $B,C in K^{ntimes m}$ are two distinct right-inverses for $A$. Then, $AB=I_{n}$ and $AC=I_{n}$. Then we have $AB+AC=2I_{n} iff A(dfrac{1}{2}(B+C))=I_{n}$.



Then $dfrac{1}{2}(B+C) in K^{m times n}$ is also a right-inverse for $A$. I think repeating this process I could prove the proposition, but I'm not really sure. Is there another way? (without Gauss-Jordan algorithm)










share|cite|improve this question


















  • 1




    If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
    – copper.hat
    Nov 17 at 5:10










  • Thanks a lot !
    – Abraham Hernández
    Nov 17 at 5:18













up vote
-1
down vote

favorite









up vote
-1
down vote

favorite











Let $A in mathbb{Q}^{mtimes n}$. Proof that if A has at least two distinct right-inverses, then A has infinitely many right-inverses.



I began this proof as follows:



Let suppose that $B,C in K^{ntimes m}$ are two distinct right-inverses for $A$. Then, $AB=I_{n}$ and $AC=I_{n}$. Then we have $AB+AC=2I_{n} iff A(dfrac{1}{2}(B+C))=I_{n}$.



Then $dfrac{1}{2}(B+C) in K^{m times n}$ is also a right-inverse for $A$. I think repeating this process I could prove the proposition, but I'm not really sure. Is there another way? (without Gauss-Jordan algorithm)










share|cite|improve this question













Let $A in mathbb{Q}^{mtimes n}$. Proof that if A has at least two distinct right-inverses, then A has infinitely many right-inverses.



I began this proof as follows:



Let suppose that $B,C in K^{ntimes m}$ are two distinct right-inverses for $A$. Then, $AB=I_{n}$ and $AC=I_{n}$. Then we have $AB+AC=2I_{n} iff A(dfrac{1}{2}(B+C))=I_{n}$.



Then $dfrac{1}{2}(B+C) in K^{m times n}$ is also a right-inverse for $A$. I think repeating this process I could prove the proposition, but I'm not really sure. Is there another way? (without Gauss-Jordan algorithm)







linear-algebra matrices






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 17 at 5:07









Abraham Hernández

31




31








  • 1




    If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
    – copper.hat
    Nov 17 at 5:10










  • Thanks a lot !
    – Abraham Hernández
    Nov 17 at 5:18














  • 1




    If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
    – copper.hat
    Nov 17 at 5:10










  • Thanks a lot !
    – Abraham Hernández
    Nov 17 at 5:18








1




1




If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
– copper.hat
Nov 17 at 5:10




If $AB=AC=I$ then $A(tB+(1-t)C) = I$ for any scalar $t$.
– copper.hat
Nov 17 at 5:10












Thanks a lot !
– Abraham Hernández
Nov 17 at 5:18




Thanks a lot !
– Abraham Hernández
Nov 17 at 5:18















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