Find the minimum distance from the point a to the set $X={ x=(x_1,x_2,…x_n)mid b_1x_1+b_2x_2+…+b_nx_n=c...












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Find the minimum distance from the point $a=(a_1,a_2,...a_n)$ to the set $$X={ x=(x_1,x_2,...x_n)mid b_1x_1+b_2x_2+...+b_nx_n=c }$$



where $ b_1^2 + b_2^2 +...+ b_n^2 gt 0 $ and $b_1, b_2,...,b_n,c in Bbb R$.



I have found so far the definition of distance from a point to a set in different books where stands that if (X,d) is a metric space $Esubset X$, $Eneq varnothing$ and $xin X$ we can define the distance from the point x to the set E in the following way



$$d(x,E):=Inf{d(x,y): y in E}$$



but I have not found any example that could help me solve this problem, and I have no Idea of how to approach it










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    $begingroup$


    Find the minimum distance from the point $a=(a_1,a_2,...a_n)$ to the set $$X={ x=(x_1,x_2,...x_n)mid b_1x_1+b_2x_2+...+b_nx_n=c }$$



    where $ b_1^2 + b_2^2 +...+ b_n^2 gt 0 $ and $b_1, b_2,...,b_n,c in Bbb R$.



    I have found so far the definition of distance from a point to a set in different books where stands that if (X,d) is a metric space $Esubset X$, $Eneq varnothing$ and $xin X$ we can define the distance from the point x to the set E in the following way



    $$d(x,E):=Inf{d(x,y): y in E}$$



    but I have not found any example that could help me solve this problem, and I have no Idea of how to approach it










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Find the minimum distance from the point $a=(a_1,a_2,...a_n)$ to the set $$X={ x=(x_1,x_2,...x_n)mid b_1x_1+b_2x_2+...+b_nx_n=c }$$



      where $ b_1^2 + b_2^2 +...+ b_n^2 gt 0 $ and $b_1, b_2,...,b_n,c in Bbb R$.



      I have found so far the definition of distance from a point to a set in different books where stands that if (X,d) is a metric space $Esubset X$, $Eneq varnothing$ and $xin X$ we can define the distance from the point x to the set E in the following way



      $$d(x,E):=Inf{d(x,y): y in E}$$



      but I have not found any example that could help me solve this problem, and I have no Idea of how to approach it










      share|cite|improve this question











      $endgroup$




      Find the minimum distance from the point $a=(a_1,a_2,...a_n)$ to the set $$X={ x=(x_1,x_2,...x_n)mid b_1x_1+b_2x_2+...+b_nx_n=c }$$



      where $ b_1^2 + b_2^2 +...+ b_n^2 gt 0 $ and $b_1, b_2,...,b_n,c in Bbb R$.



      I have found so far the definition of distance from a point to a set in different books where stands that if (X,d) is a metric space $Esubset X$, $Eneq varnothing$ and $xin X$ we can define the distance from the point x to the set E in the following way



      $$d(x,E):=Inf{d(x,y): y in E}$$



      but I have not found any example that could help me solve this problem, and I have no Idea of how to approach it







      linear-algebra multivariable-calculus






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      edited Jan 14 at 7:09







      Iván Galeana Aguilar

















      asked Jan 14 at 7:03









      Iván Galeana AguilarIván Galeana Aguilar

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      1389






















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          The method of Lagrange Multipliers tells you how to find the minimum value of $sumlimits_{k=1}^{n} (x_i-a_i)^{2}$ subject to the condition $sumlimits_{k=1}^{n} b_ix_i=c$. Consider the function $sumlimits_{k=1}^{n} (x_i-a_i)^{2} -lambda (sumlimits_{k=1}^{n} b_ix_i-c)$ where $lambda$ is a new parameter. The point where the minimum occurs can be found by setting derivatives w.r.t $x_1,x_2,cdots,x_n,lambda$ equal to $0$. This gives $2(x_k-a_k)-lambda b_k=0$ for eaxh $k leq n$. Solve this for $x_k$ in terms of $lambda$ and then use the given condition $sumlimits_{k=1}^{n} b_ix_i=c$ to find the value of $lambda$.






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            $begingroup$

            The method of Lagrange Multipliers tells you how to find the minimum value of $sumlimits_{k=1}^{n} (x_i-a_i)^{2}$ subject to the condition $sumlimits_{k=1}^{n} b_ix_i=c$. Consider the function $sumlimits_{k=1}^{n} (x_i-a_i)^{2} -lambda (sumlimits_{k=1}^{n} b_ix_i-c)$ where $lambda$ is a new parameter. The point where the minimum occurs can be found by setting derivatives w.r.t $x_1,x_2,cdots,x_n,lambda$ equal to $0$. This gives $2(x_k-a_k)-lambda b_k=0$ for eaxh $k leq n$. Solve this for $x_k$ in terms of $lambda$ and then use the given condition $sumlimits_{k=1}^{n} b_ix_i=c$ to find the value of $lambda$.






            share|cite|improve this answer









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              5












              $begingroup$

              The method of Lagrange Multipliers tells you how to find the minimum value of $sumlimits_{k=1}^{n} (x_i-a_i)^{2}$ subject to the condition $sumlimits_{k=1}^{n} b_ix_i=c$. Consider the function $sumlimits_{k=1}^{n} (x_i-a_i)^{2} -lambda (sumlimits_{k=1}^{n} b_ix_i-c)$ where $lambda$ is a new parameter. The point where the minimum occurs can be found by setting derivatives w.r.t $x_1,x_2,cdots,x_n,lambda$ equal to $0$. This gives $2(x_k-a_k)-lambda b_k=0$ for eaxh $k leq n$. Solve this for $x_k$ in terms of $lambda$ and then use the given condition $sumlimits_{k=1}^{n} b_ix_i=c$ to find the value of $lambda$.






              share|cite|improve this answer









              $endgroup$
















                5












                5








                5





                $begingroup$

                The method of Lagrange Multipliers tells you how to find the minimum value of $sumlimits_{k=1}^{n} (x_i-a_i)^{2}$ subject to the condition $sumlimits_{k=1}^{n} b_ix_i=c$. Consider the function $sumlimits_{k=1}^{n} (x_i-a_i)^{2} -lambda (sumlimits_{k=1}^{n} b_ix_i-c)$ where $lambda$ is a new parameter. The point where the minimum occurs can be found by setting derivatives w.r.t $x_1,x_2,cdots,x_n,lambda$ equal to $0$. This gives $2(x_k-a_k)-lambda b_k=0$ for eaxh $k leq n$. Solve this for $x_k$ in terms of $lambda$ and then use the given condition $sumlimits_{k=1}^{n} b_ix_i=c$ to find the value of $lambda$.






                share|cite|improve this answer









                $endgroup$



                The method of Lagrange Multipliers tells you how to find the minimum value of $sumlimits_{k=1}^{n} (x_i-a_i)^{2}$ subject to the condition $sumlimits_{k=1}^{n} b_ix_i=c$. Consider the function $sumlimits_{k=1}^{n} (x_i-a_i)^{2} -lambda (sumlimits_{k=1}^{n} b_ix_i-c)$ where $lambda$ is a new parameter. The point where the minimum occurs can be found by setting derivatives w.r.t $x_1,x_2,cdots,x_n,lambda$ equal to $0$. This gives $2(x_k-a_k)-lambda b_k=0$ for eaxh $k leq n$. Solve this for $x_k$ in terms of $lambda$ and then use the given condition $sumlimits_{k=1}^{n} b_ix_i=c$ to find the value of $lambda$.







                share|cite|improve this answer












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                answered Jan 14 at 7:20









                Kavi Rama MurthyKavi Rama Murthy

                69.1k53169




                69.1k53169






























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