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I have a homework assignment which is: You have a matrix which is regular ($ A * A' = I$ ), and the sum of each row = $C$. Prove that the sum of each row in A' are equal ( $= D$ ). And then find the relation between $C$ and $D$.

I am having trouble with this question - could someone please help me out? Thanks

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    The Inverse of $A$2011-11-28

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Let $v$ be the all-ones vector. Then $Av$ is the all-$C$ vector, and A'Av=Iv=v. But also A'Av=A'(Av). So A'(Av)=v, and $Av$ is the all-$C$ vector; what does that tell you about the row sums in A'?

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    Great :) Thanks alot2011-11-28