Determining a matrix representation of a linear transformation relative to a basis












0














T: $R^4$ to P2 defined by T(a1, a2, a3, a4)=(a1+a2)+(a2+a3)x+(a3+a4)$x^2$



B={ (1,1,1,1), (1,1,1,0), (1,1,0,0), (1,0,0,0) }



C=( 1, 1+x, 1+$x^2$ )



Question: Find the matrix representation relative to the basis B and basis C



Attempt:



T(1,1,1,1)=2+2x+2$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,1,0)=2+2x+$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,0,0)=2+x=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,0,0,0)=1=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



After solving for a,b,c,d I get the matrix



$begin{bmatrix}-2 & -1 & 1\ 2 & 2 & 1\ 2 & 1 & 0end{bmatrix}$










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  • Where is $x$ defined? How can you have a quadratic term in a linear transformation?
    – saulspatz
    Apr 14 '18 at 23:42






  • 1




    A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
    – Gerry Myerson
    Apr 15 '18 at 1:36








  • 1




    To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
    – Gerry Myerson
    Apr 15 '18 at 1:37








  • 1




    So, can you get the full answer now, Essie?
    – Gerry Myerson
    Apr 16 '18 at 2:31






  • 1




    I'm voting to close this question as off-topic because OP has abandoned it.
    – Gerry Myerson
    Apr 17 '18 at 5:38
















0














T: $R^4$ to P2 defined by T(a1, a2, a3, a4)=(a1+a2)+(a2+a3)x+(a3+a4)$x^2$



B={ (1,1,1,1), (1,1,1,0), (1,1,0,0), (1,0,0,0) }



C=( 1, 1+x, 1+$x^2$ )



Question: Find the matrix representation relative to the basis B and basis C



Attempt:



T(1,1,1,1)=2+2x+2$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,1,0)=2+2x+$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,0,0)=2+x=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,0,0,0)=1=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



After solving for a,b,c,d I get the matrix



$begin{bmatrix}-2 & -1 & 1\ 2 & 2 & 1\ 2 & 1 & 0end{bmatrix}$










share|cite|improve this question






















  • Where is $x$ defined? How can you have a quadratic term in a linear transformation?
    – saulspatz
    Apr 14 '18 at 23:42






  • 1




    A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
    – Gerry Myerson
    Apr 15 '18 at 1:36








  • 1




    To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
    – Gerry Myerson
    Apr 15 '18 at 1:37








  • 1




    So, can you get the full answer now, Essie?
    – Gerry Myerson
    Apr 16 '18 at 2:31






  • 1




    I'm voting to close this question as off-topic because OP has abandoned it.
    – Gerry Myerson
    Apr 17 '18 at 5:38














0












0








0







T: $R^4$ to P2 defined by T(a1, a2, a3, a4)=(a1+a2)+(a2+a3)x+(a3+a4)$x^2$



B={ (1,1,1,1), (1,1,1,0), (1,1,0,0), (1,0,0,0) }



C=( 1, 1+x, 1+$x^2$ )



Question: Find the matrix representation relative to the basis B and basis C



Attempt:



T(1,1,1,1)=2+2x+2$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,1,0)=2+2x+$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,0,0)=2+x=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,0,0,0)=1=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



After solving for a,b,c,d I get the matrix



$begin{bmatrix}-2 & -1 & 1\ 2 & 2 & 1\ 2 & 1 & 0end{bmatrix}$










share|cite|improve this question













T: $R^4$ to P2 defined by T(a1, a2, a3, a4)=(a1+a2)+(a2+a3)x+(a3+a4)$x^2$



B={ (1,1,1,1), (1,1,1,0), (1,1,0,0), (1,0,0,0) }



C=( 1, 1+x, 1+$x^2$ )



Question: Find the matrix representation relative to the basis B and basis C



Attempt:



T(1,1,1,1)=2+2x+2$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,1,0)=2+2x+$x^2$=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,1,0,0)=2+x=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



T(1,0,0,0)=1=a(1,1,1,1)+b(1,1,1,0)+c(1,1,0,0)+d(1,0,0,0)



After solving for a,b,c,d I get the matrix



$begin{bmatrix}-2 & -1 & 1\ 2 & 2 & 1\ 2 & 1 & 0end{bmatrix}$







matrices linear-transformations






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asked Apr 14 '18 at 23:38









EssieEssie

535




535












  • Where is $x$ defined? How can you have a quadratic term in a linear transformation?
    – saulspatz
    Apr 14 '18 at 23:42






  • 1




    A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
    – Gerry Myerson
    Apr 15 '18 at 1:36








  • 1




    To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
    – Gerry Myerson
    Apr 15 '18 at 1:37








  • 1




    So, can you get the full answer now, Essie?
    – Gerry Myerson
    Apr 16 '18 at 2:31






  • 1




    I'm voting to close this question as off-topic because OP has abandoned it.
    – Gerry Myerson
    Apr 17 '18 at 5:38


















  • Where is $x$ defined? How can you have a quadratic term in a linear transformation?
    – saulspatz
    Apr 14 '18 at 23:42






  • 1




    A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
    – Gerry Myerson
    Apr 15 '18 at 1:36








  • 1




    To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
    – Gerry Myerson
    Apr 15 '18 at 1:37








  • 1




    So, can you get the full answer now, Essie?
    – Gerry Myerson
    Apr 16 '18 at 2:31






  • 1




    I'm voting to close this question as off-topic because OP has abandoned it.
    – Gerry Myerson
    Apr 17 '18 at 5:38
















Where is $x$ defined? How can you have a quadratic term in a linear transformation?
– saulspatz
Apr 14 '18 at 23:42




Where is $x$ defined? How can you have a quadratic term in a linear transformation?
– saulspatz
Apr 14 '18 at 23:42




1




1




A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
– Gerry Myerson
Apr 15 '18 at 1:36






A linear transformation from a 4-dimensional vector space to a 3-dimensional space will have a $3times4$ matrix, not a $3times3$.
– Gerry Myerson
Apr 15 '18 at 1:36






1




1




To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
– Gerry Myerson
Apr 15 '18 at 1:37






To get you started: $2+2x+2x^2=(-2)(1)+(2)(1+x)+(2)(1+x^2)$ So your first column is certainly correct. You have just left out the 4th column.
– Gerry Myerson
Apr 15 '18 at 1:37






1




1




So, can you get the full answer now, Essie?
– Gerry Myerson
Apr 16 '18 at 2:31




So, can you get the full answer now, Essie?
– Gerry Myerson
Apr 16 '18 at 2:31




1




1




I'm voting to close this question as off-topic because OP has abandoned it.
– Gerry Myerson
Apr 17 '18 at 5:38




I'm voting to close this question as off-topic because OP has abandoned it.
– Gerry Myerson
Apr 17 '18 at 5:38










1 Answer
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You should express the results of your four transformations in terms of the ordered basis $mathscr C,$ not $mathscr B$ (it appears that you did that to get a partially-correct answer, but your attempt suggests some incomplete understanding):
$$begin{align}
T(1,1,1,1) & = 2 + 2x + 2x^2\
& = -2(1) + 2(1+x) + 2(1+x^2)\\
T(1,1,1,0) & = 2 + 2x + x^2\
& = -1(1) + 2(1+x) + 1(1+x^2)\\
T(1,1,0,0) & = 2 + x\
& = 1(1) + 1(1+x) + 0(1+x^2)\\
T(1,0,0,0) & = 1\
& = 1(1) + 0(1+x) + 0(1+x^2).end{align}$$

The coefficients of the elements of $mathscr C$ are the columns of the matrix of $T$ relative to $mathscr B$ and $mathscr C:$
$$begin{bmatrix}
-2 & -1 & 1 & 1\
2 & 2 & 1 & 0\
2 & 1 & 0 & 0end{bmatrix}.$$






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    You should express the results of your four transformations in terms of the ordered basis $mathscr C,$ not $mathscr B$ (it appears that you did that to get a partially-correct answer, but your attempt suggests some incomplete understanding):
    $$begin{align}
    T(1,1,1,1) & = 2 + 2x + 2x^2\
    & = -2(1) + 2(1+x) + 2(1+x^2)\\
    T(1,1,1,0) & = 2 + 2x + x^2\
    & = -1(1) + 2(1+x) + 1(1+x^2)\\
    T(1,1,0,0) & = 2 + x\
    & = 1(1) + 1(1+x) + 0(1+x^2)\\
    T(1,0,0,0) & = 1\
    & = 1(1) + 0(1+x) + 0(1+x^2).end{align}$$

    The coefficients of the elements of $mathscr C$ are the columns of the matrix of $T$ relative to $mathscr B$ and $mathscr C:$
    $$begin{bmatrix}
    -2 & -1 & 1 & 1\
    2 & 2 & 1 & 0\
    2 & 1 & 0 & 0end{bmatrix}.$$






    share|cite|improve this answer


























      1














      You should express the results of your four transformations in terms of the ordered basis $mathscr C,$ not $mathscr B$ (it appears that you did that to get a partially-correct answer, but your attempt suggests some incomplete understanding):
      $$begin{align}
      T(1,1,1,1) & = 2 + 2x + 2x^2\
      & = -2(1) + 2(1+x) + 2(1+x^2)\\
      T(1,1,1,0) & = 2 + 2x + x^2\
      & = -1(1) + 2(1+x) + 1(1+x^2)\\
      T(1,1,0,0) & = 2 + x\
      & = 1(1) + 1(1+x) + 0(1+x^2)\\
      T(1,0,0,0) & = 1\
      & = 1(1) + 0(1+x) + 0(1+x^2).end{align}$$

      The coefficients of the elements of $mathscr C$ are the columns of the matrix of $T$ relative to $mathscr B$ and $mathscr C:$
      $$begin{bmatrix}
      -2 & -1 & 1 & 1\
      2 & 2 & 1 & 0\
      2 & 1 & 0 & 0end{bmatrix}.$$






      share|cite|improve this answer
























        1












        1








        1






        You should express the results of your four transformations in terms of the ordered basis $mathscr C,$ not $mathscr B$ (it appears that you did that to get a partially-correct answer, but your attempt suggests some incomplete understanding):
        $$begin{align}
        T(1,1,1,1) & = 2 + 2x + 2x^2\
        & = -2(1) + 2(1+x) + 2(1+x^2)\\
        T(1,1,1,0) & = 2 + 2x + x^2\
        & = -1(1) + 2(1+x) + 1(1+x^2)\\
        T(1,1,0,0) & = 2 + x\
        & = 1(1) + 1(1+x) + 0(1+x^2)\\
        T(1,0,0,0) & = 1\
        & = 1(1) + 0(1+x) + 0(1+x^2).end{align}$$

        The coefficients of the elements of $mathscr C$ are the columns of the matrix of $T$ relative to $mathscr B$ and $mathscr C:$
        $$begin{bmatrix}
        -2 & -1 & 1 & 1\
        2 & 2 & 1 & 0\
        2 & 1 & 0 & 0end{bmatrix}.$$






        share|cite|improve this answer












        You should express the results of your four transformations in terms of the ordered basis $mathscr C,$ not $mathscr B$ (it appears that you did that to get a partially-correct answer, but your attempt suggests some incomplete understanding):
        $$begin{align}
        T(1,1,1,1) & = 2 + 2x + 2x^2\
        & = -2(1) + 2(1+x) + 2(1+x^2)\\
        T(1,1,1,0) & = 2 + 2x + x^2\
        & = -1(1) + 2(1+x) + 1(1+x^2)\\
        T(1,1,0,0) & = 2 + x\
        & = 1(1) + 1(1+x) + 0(1+x^2)\\
        T(1,0,0,0) & = 1\
        & = 1(1) + 0(1+x) + 0(1+x^2).end{align}$$

        The coefficients of the elements of $mathscr C$ are the columns of the matrix of $T$ relative to $mathscr B$ and $mathscr C:$
        $$begin{bmatrix}
        -2 & -1 & 1 & 1\
        2 & 2 & 1 & 0\
        2 & 1 & 0 & 0end{bmatrix}.$$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 21 '18 at 17:52









        Maurice PMaurice P

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        1,3901732






























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