compute sum of the components of the solution to a linear equation

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Given $A x = b$, where $Ain mathbb R^ntimes n$ is invertible. Let $x=(x_1, cdots, x_n)^T$. How to compute $sum_i=1^n x_i$ without solving the equation? For a given $Cin mathbb R$, how to check if $x_1+cdots +x_n = C$ is consistent with $Ax=b$ without solving the equation?







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  • I guess you are not allowed to compute the inverse of $A$?
    – lanskey
    Jul 19 at 21:43










  • No. Don't want to compute the inverse of $A$.
    – user32828
    Jul 19 at 21:58














up vote
0
down vote

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Given $A x = b$, where $Ain mathbb R^ntimes n$ is invertible. Let $x=(x_1, cdots, x_n)^T$. How to compute $sum_i=1^n x_i$ without solving the equation? For a given $Cin mathbb R$, how to check if $x_1+cdots +x_n = C$ is consistent with $Ax=b$ without solving the equation?







share|cite|improve this question



















  • I guess you are not allowed to compute the inverse of $A$?
    – lanskey
    Jul 19 at 21:43










  • No. Don't want to compute the inverse of $A$.
    – user32828
    Jul 19 at 21:58












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Given $A x = b$, where $Ain mathbb R^ntimes n$ is invertible. Let $x=(x_1, cdots, x_n)^T$. How to compute $sum_i=1^n x_i$ without solving the equation? For a given $Cin mathbb R$, how to check if $x_1+cdots +x_n = C$ is consistent with $Ax=b$ without solving the equation?







share|cite|improve this question











Given $A x = b$, where $Ain mathbb R^ntimes n$ is invertible. Let $x=(x_1, cdots, x_n)^T$. How to compute $sum_i=1^n x_i$ without solving the equation? For a given $Cin mathbb R$, how to check if $x_1+cdots +x_n = C$ is consistent with $Ax=b$ without solving the equation?









share|cite|improve this question










share|cite|improve this question




share|cite|improve this question









asked Jul 19 at 18:57









user32828

1409




1409











  • I guess you are not allowed to compute the inverse of $A$?
    – lanskey
    Jul 19 at 21:43










  • No. Don't want to compute the inverse of $A$.
    – user32828
    Jul 19 at 21:58
















  • I guess you are not allowed to compute the inverse of $A$?
    – lanskey
    Jul 19 at 21:43










  • No. Don't want to compute the inverse of $A$.
    – user32828
    Jul 19 at 21:58















I guess you are not allowed to compute the inverse of $A$?
– lanskey
Jul 19 at 21:43




I guess you are not allowed to compute the inverse of $A$?
– lanskey
Jul 19 at 21:43












No. Don't want to compute the inverse of $A$.
– user32828
Jul 19 at 21:58




No. Don't want to compute the inverse of $A$.
– user32828
Jul 19 at 21:58















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