Compute $text{rk}(p)$ using Gauss reduction on $A$. Compute $dimbig(ker(p)big)$.












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Let $B = (1, X, X^2)$ be a basis for $mathbb{R}_2[X]$ and $p ∈ mathcal{L}big(mathbb{R}_2[X]big)$ be the linear map defined by $p(1) = frac{1}{3}(2 − X − X^2)$, $p(X) = frac{1}{3}(−1 + 2X − X^2)$ and $p(X^2) = frac{1}{3} (−1 − X + 2X^2)$.



By definition of the task, I found that $A=M_B(p)$, which is the matrix of
$p$ with respect to the basis $B$.



begin{bmatrix}
frac{2}{3} & -frac{1}{3} & -frac{1}{3} \
-frac{1}{3} & frac{2}{3} & -frac{1}{3} \
-frac{1}{3} & -frac{1}{3} &frac{2}{3} \
end{bmatrix}



Compute $text{rk}(p)$ using Gauss reduction on $A$. Compute $dimbig(ker(p)big)$.



I found $text{rk}(p)$ which is $2$. I looked at the definition of $ker$, and $dim(ker)$ but apparently I'm quite struggling to find it. How should I go about it?










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    0












    $begingroup$


    Let $B = (1, X, X^2)$ be a basis for $mathbb{R}_2[X]$ and $p ∈ mathcal{L}big(mathbb{R}_2[X]big)$ be the linear map defined by $p(1) = frac{1}{3}(2 − X − X^2)$, $p(X) = frac{1}{3}(−1 + 2X − X^2)$ and $p(X^2) = frac{1}{3} (−1 − X + 2X^2)$.



    By definition of the task, I found that $A=M_B(p)$, which is the matrix of
    $p$ with respect to the basis $B$.



    begin{bmatrix}
    frac{2}{3} & -frac{1}{3} & -frac{1}{3} \
    -frac{1}{3} & frac{2}{3} & -frac{1}{3} \
    -frac{1}{3} & -frac{1}{3} &frac{2}{3} \
    end{bmatrix}



    Compute $text{rk}(p)$ using Gauss reduction on $A$. Compute $dimbig(ker(p)big)$.



    I found $text{rk}(p)$ which is $2$. I looked at the definition of $ker$, and $dim(ker)$ but apparently I'm quite struggling to find it. How should I go about it?










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Let $B = (1, X, X^2)$ be a basis for $mathbb{R}_2[X]$ and $p ∈ mathcal{L}big(mathbb{R}_2[X]big)$ be the linear map defined by $p(1) = frac{1}{3}(2 − X − X^2)$, $p(X) = frac{1}{3}(−1 + 2X − X^2)$ and $p(X^2) = frac{1}{3} (−1 − X + 2X^2)$.



      By definition of the task, I found that $A=M_B(p)$, which is the matrix of
      $p$ with respect to the basis $B$.



      begin{bmatrix}
      frac{2}{3} & -frac{1}{3} & -frac{1}{3} \
      -frac{1}{3} & frac{2}{3} & -frac{1}{3} \
      -frac{1}{3} & -frac{1}{3} &frac{2}{3} \
      end{bmatrix}



      Compute $text{rk}(p)$ using Gauss reduction on $A$. Compute $dimbig(ker(p)big)$.



      I found $text{rk}(p)$ which is $2$. I looked at the definition of $ker$, and $dim(ker)$ but apparently I'm quite struggling to find it. How should I go about it?










      share|cite|improve this question











      $endgroup$




      Let $B = (1, X, X^2)$ be a basis for $mathbb{R}_2[X]$ and $p ∈ mathcal{L}big(mathbb{R}_2[X]big)$ be the linear map defined by $p(1) = frac{1}{3}(2 − X − X^2)$, $p(X) = frac{1}{3}(−1 + 2X − X^2)$ and $p(X^2) = frac{1}{3} (−1 − X + 2X^2)$.



      By definition of the task, I found that $A=M_B(p)$, which is the matrix of
      $p$ with respect to the basis $B$.



      begin{bmatrix}
      frac{2}{3} & -frac{1}{3} & -frac{1}{3} \
      -frac{1}{3} & frac{2}{3} & -frac{1}{3} \
      -frac{1}{3} & -frac{1}{3} &frac{2}{3} \
      end{bmatrix}



      Compute $text{rk}(p)$ using Gauss reduction on $A$. Compute $dimbig(ker(p)big)$.



      I found $text{rk}(p)$ which is $2$. I looked at the definition of $ker$, and $dim(ker)$ but apparently I'm quite struggling to find it. How should I go about it?







      linear-algebra matrices linear-transformations matrix-rank change-of-basis






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      edited Dec 15 '18 at 12:20









      Batominovski

      33k33293




      33k33293










      asked Dec 13 '18 at 17:02









      nasdaqnasdaq

      62




      62






















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          There is a theorem called the rank-nullity theorem, which states that for a linear transformation $p:Vto W, text{rk}(p)+dim(ker(p))=dim(V)$. In your case, $dim(ker(p))=3-text{rk}(p)=3-2=1$.






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            $begingroup$

            There is a theorem called the rank-nullity theorem, which states that for a linear transformation $p:Vto W, text{rk}(p)+dim(ker(p))=dim(V)$. In your case, $dim(ker(p))=3-text{rk}(p)=3-2=1$.






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              0












              $begingroup$

              There is a theorem called the rank-nullity theorem, which states that for a linear transformation $p:Vto W, text{rk}(p)+dim(ker(p))=dim(V)$. In your case, $dim(ker(p))=3-text{rk}(p)=3-2=1$.






              share|cite|improve this answer









              $endgroup$
















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                0





                $begingroup$

                There is a theorem called the rank-nullity theorem, which states that for a linear transformation $p:Vto W, text{rk}(p)+dim(ker(p))=dim(V)$. In your case, $dim(ker(p))=3-text{rk}(p)=3-2=1$.






                share|cite|improve this answer









                $endgroup$



                There is a theorem called the rank-nullity theorem, which states that for a linear transformation $p:Vto W, text{rk}(p)+dim(ker(p))=dim(V)$. In your case, $dim(ker(p))=3-text{rk}(p)=3-2=1$.







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                share|cite|improve this answer










                answered Dec 13 '18 at 21:30









                Shubham JohriShubham Johri

                5,172717




                5,172717






























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