T/F: The Range of a Linear Transformation must be a subset of the domain.












3












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I am having difficulty understanding why it is false. As I understand, the range is the output of everything from the domain into the transformation function, or the result of the domain being outputted to the co-domain via the transformation. Essentially, I cannot think of a counterexample where the range of a linear transformation is not in the domain. I would appreciate if anyone could shed some light on this basic concept that I am struggling with.










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$endgroup$








  • 2




    $begingroup$
    Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
    $endgroup$
    – DonAntonio
    Jan 29 at 18:06






  • 2




    $begingroup$
    The range of a function is a subset of the codomain.
    $endgroup$
    – stressed out
    Jan 29 at 18:06






  • 3




    $begingroup$
    Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
    $endgroup$
    – Hyperion
    Jan 29 at 18:06
















3












$begingroup$


I am having difficulty understanding why it is false. As I understand, the range is the output of everything from the domain into the transformation function, or the result of the domain being outputted to the co-domain via the transformation. Essentially, I cannot think of a counterexample where the range of a linear transformation is not in the domain. I would appreciate if anyone could shed some light on this basic concept that I am struggling with.










share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
    $endgroup$
    – DonAntonio
    Jan 29 at 18:06






  • 2




    $begingroup$
    The range of a function is a subset of the codomain.
    $endgroup$
    – stressed out
    Jan 29 at 18:06






  • 3




    $begingroup$
    Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
    $endgroup$
    – Hyperion
    Jan 29 at 18:06














3












3








3


0



$begingroup$


I am having difficulty understanding why it is false. As I understand, the range is the output of everything from the domain into the transformation function, or the result of the domain being outputted to the co-domain via the transformation. Essentially, I cannot think of a counterexample where the range of a linear transformation is not in the domain. I would appreciate if anyone could shed some light on this basic concept that I am struggling with.










share|cite|improve this question









$endgroup$




I am having difficulty understanding why it is false. As I understand, the range is the output of everything from the domain into the transformation function, or the result of the domain being outputted to the co-domain via the transformation. Essentially, I cannot think of a counterexample where the range of a linear transformation is not in the domain. I would appreciate if anyone could shed some light on this basic concept that I am struggling with.







linear-algebra linear-transformations






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asked Jan 29 at 18:03









TrebondTrebond

463




463








  • 2




    $begingroup$
    Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
    $endgroup$
    – DonAntonio
    Jan 29 at 18:06






  • 2




    $begingroup$
    The range of a function is a subset of the codomain.
    $endgroup$
    – stressed out
    Jan 29 at 18:06






  • 3




    $begingroup$
    Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
    $endgroup$
    – Hyperion
    Jan 29 at 18:06














  • 2




    $begingroup$
    Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
    $endgroup$
    – DonAntonio
    Jan 29 at 18:06






  • 2




    $begingroup$
    The range of a function is a subset of the codomain.
    $endgroup$
    – stressed out
    Jan 29 at 18:06






  • 3




    $begingroup$
    Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
    $endgroup$
    – Hyperion
    Jan 29 at 18:06








2




2




$begingroup$
Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
$endgroup$
– DonAntonio
Jan 29 at 18:06




$begingroup$
Because the range of any function is always a subset of the codomain. Thus, if you have a linear transformation $;T: Vto W;$ , its range is a subset (in fact, a subspace) of $;W;$ .
$endgroup$
– DonAntonio
Jan 29 at 18:06




2




2




$begingroup$
The range of a function is a subset of the codomain.
$endgroup$
– stressed out
Jan 29 at 18:06




$begingroup$
The range of a function is a subset of the codomain.
$endgroup$
– stressed out
Jan 29 at 18:06




3




3




$begingroup$
Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
$endgroup$
– Hyperion
Jan 29 at 18:06




$begingroup$
Think of a linear transformation from $mathbb{R}^4 rightarrow mathbb{R}^3$ through a matrix of transformation $A$. $mathbb{R}^3$ is not a subset of $mathbb{R}^4$.
$endgroup$
– Hyperion
Jan 29 at 18:06










2 Answers
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3












$begingroup$

Consider the following example of linear transformation,




$T:mathbb R to {mathbb R}^2$



$T(x)= (x,0)$




Note that Range of $T$ is {$(x,0):x in mathbb R$} which is not a subset of the domain (i.e. $mathbb R$).






share|cite|improve this answer









$endgroup$





















    2












    $begingroup$

    Take $Fcolonmathbb{R}longrightarrowmathbb{R}[x]$ defined by $F(lambda)=lambda x$. Its range is a set of polynomials, and therefore it is not a subset of $mathbb R$.






    share|cite|improve this answer









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      2 Answers
      2






      active

      oldest

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      2 Answers
      2






      active

      oldest

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      active

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      active

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      3












      $begingroup$

      Consider the following example of linear transformation,




      $T:mathbb R to {mathbb R}^2$



      $T(x)= (x,0)$




      Note that Range of $T$ is {$(x,0):x in mathbb R$} which is not a subset of the domain (i.e. $mathbb R$).






      share|cite|improve this answer









      $endgroup$


















        3












        $begingroup$

        Consider the following example of linear transformation,




        $T:mathbb R to {mathbb R}^2$



        $T(x)= (x,0)$




        Note that Range of $T$ is {$(x,0):x in mathbb R$} which is not a subset of the domain (i.e. $mathbb R$).






        share|cite|improve this answer









        $endgroup$
















          3












          3








          3





          $begingroup$

          Consider the following example of linear transformation,




          $T:mathbb R to {mathbb R}^2$



          $T(x)= (x,0)$




          Note that Range of $T$ is {$(x,0):x in mathbb R$} which is not a subset of the domain (i.e. $mathbb R$).






          share|cite|improve this answer









          $endgroup$



          Consider the following example of linear transformation,




          $T:mathbb R to {mathbb R}^2$



          $T(x)= (x,0)$




          Note that Range of $T$ is {$(x,0):x in mathbb R$} which is not a subset of the domain (i.e. $mathbb R$).







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 29 at 18:15









          Mayuresh LMayuresh L

          1,331323




          1,331323























              2












              $begingroup$

              Take $Fcolonmathbb{R}longrightarrowmathbb{R}[x]$ defined by $F(lambda)=lambda x$. Its range is a set of polynomials, and therefore it is not a subset of $mathbb R$.






              share|cite|improve this answer









              $endgroup$


















                2












                $begingroup$

                Take $Fcolonmathbb{R}longrightarrowmathbb{R}[x]$ defined by $F(lambda)=lambda x$. Its range is a set of polynomials, and therefore it is not a subset of $mathbb R$.






                share|cite|improve this answer









                $endgroup$
















                  2












                  2








                  2





                  $begingroup$

                  Take $Fcolonmathbb{R}longrightarrowmathbb{R}[x]$ defined by $F(lambda)=lambda x$. Its range is a set of polynomials, and therefore it is not a subset of $mathbb R$.






                  share|cite|improve this answer









                  $endgroup$



                  Take $Fcolonmathbb{R}longrightarrowmathbb{R}[x]$ defined by $F(lambda)=lambda x$. Its range is a set of polynomials, and therefore it is not a subset of $mathbb R$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 29 at 18:11









                  José Carlos SantosJosé Carlos Santos

                  171k23132240




                  171k23132240






























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