Finding kernel and range of a linear transformation












7












$begingroup$


We are given:




Find $ker(T)$, and $textrm{rng}(T)$, where $T$ is the linear transformation given by



$$T:mathbb{R^3} rightarrow mathbb{R^3}$$



with standard matrix



$$ A = left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]textrm{.}
$$




The kernel can be found in a $2 times 2$ matrix as follows:



$$ L = left[begin{array}{rrr}
a & b\
c & d\
end{array}right] = (a+d) + (b+c)t
$$



Then to find the kernel of $L$ we set



$$(a+d) + (b+c)t = 0$$
$$d = -a$$
$$c = -b$$



so that the kernel of $L$ is the set of all matrices of the form
$$ A = left[begin{array}{rrr}
a & b\
-b & -a\
end{array}right]
$$



but I do not know how to apply that to this problem.










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$endgroup$








  • 3




    $begingroup$
    Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
    $endgroup$
    – user137731
    May 31 '15 at 0:56


















7












$begingroup$


We are given:




Find $ker(T)$, and $textrm{rng}(T)$, where $T$ is the linear transformation given by



$$T:mathbb{R^3} rightarrow mathbb{R^3}$$



with standard matrix



$$ A = left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]textrm{.}
$$




The kernel can be found in a $2 times 2$ matrix as follows:



$$ L = left[begin{array}{rrr}
a & b\
c & d\
end{array}right] = (a+d) + (b+c)t
$$



Then to find the kernel of $L$ we set



$$(a+d) + (b+c)t = 0$$
$$d = -a$$
$$c = -b$$



so that the kernel of $L$ is the set of all matrices of the form
$$ A = left[begin{array}{rrr}
a & b\
-b & -a\
end{array}right]
$$



but I do not know how to apply that to this problem.










share|cite|improve this question











$endgroup$








  • 3




    $begingroup$
    Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
    $endgroup$
    – user137731
    May 31 '15 at 0:56
















7












7








7


3



$begingroup$


We are given:




Find $ker(T)$, and $textrm{rng}(T)$, where $T$ is the linear transformation given by



$$T:mathbb{R^3} rightarrow mathbb{R^3}$$



with standard matrix



$$ A = left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]textrm{.}
$$




The kernel can be found in a $2 times 2$ matrix as follows:



$$ L = left[begin{array}{rrr}
a & b\
c & d\
end{array}right] = (a+d) + (b+c)t
$$



Then to find the kernel of $L$ we set



$$(a+d) + (b+c)t = 0$$
$$d = -a$$
$$c = -b$$



so that the kernel of $L$ is the set of all matrices of the form
$$ A = left[begin{array}{rrr}
a & b\
-b & -a\
end{array}right]
$$



but I do not know how to apply that to this problem.










share|cite|improve this question











$endgroup$




We are given:




Find $ker(T)$, and $textrm{rng}(T)$, where $T$ is the linear transformation given by



$$T:mathbb{R^3} rightarrow mathbb{R^3}$$



with standard matrix



$$ A = left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]textrm{.}
$$




The kernel can be found in a $2 times 2$ matrix as follows:



$$ L = left[begin{array}{rrr}
a & b\
c & d\
end{array}right] = (a+d) + (b+c)t
$$



Then to find the kernel of $L$ we set



$$(a+d) + (b+c)t = 0$$
$$d = -a$$
$$c = -b$$



so that the kernel of $L$ is the set of all matrices of the form
$$ A = left[begin{array}{rrr}
a & b\
-b & -a\
end{array}right]
$$



but I do not know how to apply that to this problem.







linear-algebra linear-transformations






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited May 31 '15 at 1:07









Ken

3,63151728




3,63151728










asked May 31 '15 at 0:37









user4640007user4640007

1711213




1711213








  • 3




    $begingroup$
    Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
    $endgroup$
    – user137731
    May 31 '15 at 0:56
















  • 3




    $begingroup$
    Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
    $endgroup$
    – user137731
    May 31 '15 at 0:56










3




3




$begingroup$
Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
$endgroup$
– user137731
May 31 '15 at 0:56






$begingroup$
Kernels are defined for linear transformations, not matrices. Usually when we say the "kernel of a matrix $A$", what we really mean is the kernel of the linear transformation $x mapsto Ax$ for a column matrix $x$. The kernel in that case will be a set of column matrices. So I don't understand what you mean when you say that the kernel of $L$ is the set of matrices $begin{bmatrix} a & b \ -b & -aend{bmatrix}$. Can you expand on what exactly you mean and where this comes from?
$endgroup$
– user137731
May 31 '15 at 0:56












3 Answers
3






active

oldest

votes


















7












$begingroup$

$$
A = left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]
$$
Consider a linear map represented as a $m × n$ matrix $A$ .
The kernel of this linear map is the set of solutions to the equation $Ax = 0$
$$
ker(A)={x in R^n|Ax=0}
$$
$$
det(A)=1(12+16)-(-1)(10+28)+3(20-42)=0
$$
Since $det(A)=0$ , $xne0$ and $0$ is a vector here.
$$
left[begin{array}{rrr}
1 & -1 & 3\
5 & 6 & -4\
7 & 4 & 2\
end{array}right]
left[begin{array}{r}
a\b\c
end{array}right]
=left[begin{array}{r}
0\0\0
end{array}right]
$$
In row-reduced form,
$$
A = left[begin{array}{rrr}
1 & 0 & frac{14}{11}\
0 & 1 & frac{-19}{11}\
0 & 0 & 0\
end{array}right]
$$
$$x=frac{-14}{11}z$$
$$y=frac{19}{11}z$$
$$
left[begin{array}{r}
a\b\c
end{array}right]
=left[begin{array}{r}
-14\19\11
end{array}right]z
$$
Similarly for $2×2$ matrix .






share|cite|improve this answer











$endgroup$





















    2












    $begingroup$

    For range (T), just row reduce A to Echelon form, the remaining non-zero vectors are basis for Range space of T.






    share|cite|improve this answer









    $endgroup$





















      -1












      $begingroup$

      To find the range(image) of T, find the transpose of the matrix first and then reduce the transposed matrix to an echelon form, the remaining non zero matrix becomes the basis for the range and the dimension becomes the rank






      share|cite|improve this answer









      $endgroup$









      • 2




        $begingroup$
        Welcome to MSE. Your answer adds nothing new to the already existing answers.
        $endgroup$
        – José Carlos Santos
        Jan 23 at 13:22






      • 2




        $begingroup$
        Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
        $endgroup$
        – hardmath
        Jan 23 at 16:25











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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      7












      $begingroup$

      $$
      A = left[begin{array}{rrr}
      1 & -1 & 3\
      5 & 6 & -4\
      7 & 4 & 2\
      end{array}right]
      $$
      Consider a linear map represented as a $m × n$ matrix $A$ .
      The kernel of this linear map is the set of solutions to the equation $Ax = 0$
      $$
      ker(A)={x in R^n|Ax=0}
      $$
      $$
      det(A)=1(12+16)-(-1)(10+28)+3(20-42)=0
      $$
      Since $det(A)=0$ , $xne0$ and $0$ is a vector here.
      $$
      left[begin{array}{rrr}
      1 & -1 & 3\
      5 & 6 & -4\
      7 & 4 & 2\
      end{array}right]
      left[begin{array}{r}
      a\b\c
      end{array}right]
      =left[begin{array}{r}
      0\0\0
      end{array}right]
      $$
      In row-reduced form,
      $$
      A = left[begin{array}{rrr}
      1 & 0 & frac{14}{11}\
      0 & 1 & frac{-19}{11}\
      0 & 0 & 0\
      end{array}right]
      $$
      $$x=frac{-14}{11}z$$
      $$y=frac{19}{11}z$$
      $$
      left[begin{array}{r}
      a\b\c
      end{array}right]
      =left[begin{array}{r}
      -14\19\11
      end{array}right]z
      $$
      Similarly for $2×2$ matrix .






      share|cite|improve this answer











      $endgroup$


















        7












        $begingroup$

        $$
        A = left[begin{array}{rrr}
        1 & -1 & 3\
        5 & 6 & -4\
        7 & 4 & 2\
        end{array}right]
        $$
        Consider a linear map represented as a $m × n$ matrix $A$ .
        The kernel of this linear map is the set of solutions to the equation $Ax = 0$
        $$
        ker(A)={x in R^n|Ax=0}
        $$
        $$
        det(A)=1(12+16)-(-1)(10+28)+3(20-42)=0
        $$
        Since $det(A)=0$ , $xne0$ and $0$ is a vector here.
        $$
        left[begin{array}{rrr}
        1 & -1 & 3\
        5 & 6 & -4\
        7 & 4 & 2\
        end{array}right]
        left[begin{array}{r}
        a\b\c
        end{array}right]
        =left[begin{array}{r}
        0\0\0
        end{array}right]
        $$
        In row-reduced form,
        $$
        A = left[begin{array}{rrr}
        1 & 0 & frac{14}{11}\
        0 & 1 & frac{-19}{11}\
        0 & 0 & 0\
        end{array}right]
        $$
        $$x=frac{-14}{11}z$$
        $$y=frac{19}{11}z$$
        $$
        left[begin{array}{r}
        a\b\c
        end{array}right]
        =left[begin{array}{r}
        -14\19\11
        end{array}right]z
        $$
        Similarly for $2×2$ matrix .






        share|cite|improve this answer











        $endgroup$
















          7












          7








          7





          $begingroup$

          $$
          A = left[begin{array}{rrr}
          1 & -1 & 3\
          5 & 6 & -4\
          7 & 4 & 2\
          end{array}right]
          $$
          Consider a linear map represented as a $m × n$ matrix $A$ .
          The kernel of this linear map is the set of solutions to the equation $Ax = 0$
          $$
          ker(A)={x in R^n|Ax=0}
          $$
          $$
          det(A)=1(12+16)-(-1)(10+28)+3(20-42)=0
          $$
          Since $det(A)=0$ , $xne0$ and $0$ is a vector here.
          $$
          left[begin{array}{rrr}
          1 & -1 & 3\
          5 & 6 & -4\
          7 & 4 & 2\
          end{array}right]
          left[begin{array}{r}
          a\b\c
          end{array}right]
          =left[begin{array}{r}
          0\0\0
          end{array}right]
          $$
          In row-reduced form,
          $$
          A = left[begin{array}{rrr}
          1 & 0 & frac{14}{11}\
          0 & 1 & frac{-19}{11}\
          0 & 0 & 0\
          end{array}right]
          $$
          $$x=frac{-14}{11}z$$
          $$y=frac{19}{11}z$$
          $$
          left[begin{array}{r}
          a\b\c
          end{array}right]
          =left[begin{array}{r}
          -14\19\11
          end{array}right]z
          $$
          Similarly for $2×2$ matrix .






          share|cite|improve this answer











          $endgroup$



          $$
          A = left[begin{array}{rrr}
          1 & -1 & 3\
          5 & 6 & -4\
          7 & 4 & 2\
          end{array}right]
          $$
          Consider a linear map represented as a $m × n$ matrix $A$ .
          The kernel of this linear map is the set of solutions to the equation $Ax = 0$
          $$
          ker(A)={x in R^n|Ax=0}
          $$
          $$
          det(A)=1(12+16)-(-1)(10+28)+3(20-42)=0
          $$
          Since $det(A)=0$ , $xne0$ and $0$ is a vector here.
          $$
          left[begin{array}{rrr}
          1 & -1 & 3\
          5 & 6 & -4\
          7 & 4 & 2\
          end{array}right]
          left[begin{array}{r}
          a\b\c
          end{array}right]
          =left[begin{array}{r}
          0\0\0
          end{array}right]
          $$
          In row-reduced form,
          $$
          A = left[begin{array}{rrr}
          1 & 0 & frac{14}{11}\
          0 & 1 & frac{-19}{11}\
          0 & 0 & 0\
          end{array}right]
          $$
          $$x=frac{-14}{11}z$$
          $$y=frac{19}{11}z$$
          $$
          left[begin{array}{r}
          a\b\c
          end{array}right]
          =left[begin{array}{r}
          -14\19\11
          end{array}right]z
          $$
          Similarly for $2×2$ matrix .







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited May 31 '15 at 1:52

























          answered May 31 '15 at 1:23









          vidhanvidhan

          853315




          853315























              2












              $begingroup$

              For range (T), just row reduce A to Echelon form, the remaining non-zero vectors are basis for Range space of T.






              share|cite|improve this answer









              $endgroup$


















                2












                $begingroup$

                For range (T), just row reduce A to Echelon form, the remaining non-zero vectors are basis for Range space of T.






                share|cite|improve this answer









                $endgroup$
















                  2












                  2








                  2





                  $begingroup$

                  For range (T), just row reduce A to Echelon form, the remaining non-zero vectors are basis for Range space of T.






                  share|cite|improve this answer









                  $endgroup$



                  For range (T), just row reduce A to Echelon form, the remaining non-zero vectors are basis for Range space of T.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered May 31 '15 at 15:22









                  Sam ChristopherSam Christopher

                  585323




                  585323























                      -1












                      $begingroup$

                      To find the range(image) of T, find the transpose of the matrix first and then reduce the transposed matrix to an echelon form, the remaining non zero matrix becomes the basis for the range and the dimension becomes the rank






                      share|cite|improve this answer









                      $endgroup$









                      • 2




                        $begingroup$
                        Welcome to MSE. Your answer adds nothing new to the already existing answers.
                        $endgroup$
                        – José Carlos Santos
                        Jan 23 at 13:22






                      • 2




                        $begingroup$
                        Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                        $endgroup$
                        – hardmath
                        Jan 23 at 16:25
















                      -1












                      $begingroup$

                      To find the range(image) of T, find the transpose of the matrix first and then reduce the transposed matrix to an echelon form, the remaining non zero matrix becomes the basis for the range and the dimension becomes the rank






                      share|cite|improve this answer









                      $endgroup$









                      • 2




                        $begingroup$
                        Welcome to MSE. Your answer adds nothing new to the already existing answers.
                        $endgroup$
                        – José Carlos Santos
                        Jan 23 at 13:22






                      • 2




                        $begingroup$
                        Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                        $endgroup$
                        – hardmath
                        Jan 23 at 16:25














                      -1












                      -1








                      -1





                      $begingroup$

                      To find the range(image) of T, find the transpose of the matrix first and then reduce the transposed matrix to an echelon form, the remaining non zero matrix becomes the basis for the range and the dimension becomes the rank






                      share|cite|improve this answer









                      $endgroup$



                      To find the range(image) of T, find the transpose of the matrix first and then reduce the transposed matrix to an echelon form, the remaining non zero matrix becomes the basis for the range and the dimension becomes the rank







                      share|cite|improve this answer












                      share|cite|improve this answer



                      share|cite|improve this answer










                      answered Jan 23 at 13:01









                      sesan Amusasesan Amusa

                      1




                      1








                      • 2




                        $begingroup$
                        Welcome to MSE. Your answer adds nothing new to the already existing answers.
                        $endgroup$
                        – José Carlos Santos
                        Jan 23 at 13:22






                      • 2




                        $begingroup$
                        Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                        $endgroup$
                        – hardmath
                        Jan 23 at 16:25














                      • 2




                        $begingroup$
                        Welcome to MSE. Your answer adds nothing new to the already existing answers.
                        $endgroup$
                        – José Carlos Santos
                        Jan 23 at 13:22






                      • 2




                        $begingroup$
                        Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                        $endgroup$
                        – hardmath
                        Jan 23 at 16:25








                      2




                      2




                      $begingroup$
                      Welcome to MSE. Your answer adds nothing new to the already existing answers.
                      $endgroup$
                      – José Carlos Santos
                      Jan 23 at 13:22




                      $begingroup$
                      Welcome to MSE. Your answer adds nothing new to the already existing answers.
                      $endgroup$
                      – José Carlos Santos
                      Jan 23 at 13:22




                      2




                      2




                      $begingroup$
                      Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                      $endgroup$
                      – hardmath
                      Jan 23 at 16:25




                      $begingroup$
                      Giving a hurried and partial (you do not even mention the kernel of $T$) Answer after so much time has passed is of negligible value. When an older Question already has an Accepted and/or upvoted Answer, it is expedient to carefully highlight what new information is being added (thus demonstrating that you've considered the existing Answers and are not simply repeating the work of others).
                      $endgroup$
                      – hardmath
                      Jan 23 at 16:25


















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