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{:[x_(1)+x_(2)+2x_(3)=-1],[x_(1)-2x_(2)+x_(3)=-5],[3x_(1)+x_(2)+x_(3)=3]:}
a)Find all solutions using Gaussian elimination or Gauss-Jordan reduction.

x1+x2+2x3=1x12x2+x3=53x1+x2+x3=3 \begin{array}{l} x_{1}+x_{2}+2 x_{3}=-1 \\ x_{1}-2 x_{2}+x_{3}=-5 \\ 3 x_{1}+x_{2}+x_{3}=3 \end{array} \newlinea)Find all solutions using Gaussian elimination or Gauss-Jordan reduction.

Full solution

Q. x1+x2+2x3=1x12x2+x3=53x1+x2+x3=3 \begin{array}{l} x_{1}+x_{2}+2 x_{3}=-1 \\ x_{1}-2 x_{2}+x_{3}=-5 \\ 3 x_{1}+x_{2}+x_{3}=3 \end{array} \newlinea)Find all solutions using Gaussian elimination or Gauss-Jordan reduction.
  1. Write Matrix Form: Write down the system of equations in matrix form:\newline[112112153113] \begin{bmatrix} 1 & 1 & 2 & | & -1 \\ 1 & -2 & 1 & | & -5 \\ 3 & 1 & 1 & | & 3 \end{bmatrix}
  2. Gaussian Elimination: Begin Gaussian elimination by making the first element of the first column a 11 (if it's not already) and use it to zero out the rest of the first column:\newline- Subtract the first row from the second row.\newline- Subtract 33 times the first row from the third row.\newline[112103140256] \begin{bmatrix} 1 & 1 & 2 & | & -1 \\ 0 & -3 & -1 & | & -4 \\ 0 & -2 & -5 & | & 6 \end{bmatrix}
  3. Make Second Element 11: Make the second element of the second column a 11 by dividing the second row by 3-3:\newline[1121011/34/30256] \begin{bmatrix} 1 & 1 & 2 & | & -1 \\ 0 & 1 & 1/3 & | & 4/3 \\ 0 & -2 & -5 & | & 6 \end{bmatrix}
  4. Zero Out Second Column: Use the second row to zero out the rest of the second column:\newline- Add the second row to the first row.\newline- Add 22 times the second row to the third row.\newline[107/31/3011/34/30013/314/3] \begin{bmatrix} 1 & 0 & 7/3 & | & -1/3 \\ 0 & 1 & 1/3 & | & 4/3 \\ 0 & 0 & -13/3 & | & 14/3 \end{bmatrix}
  5. Make Third Element 11: Make the third element of the third column a 11 by dividing the third row by 13-13/33:\newline[107/31/3011/34/300114/13] \begin{bmatrix} 1 & 0 & 7/3 & | & -1/3 \\ 0 & 1 & 1/3 & | & 4/3 \\ 0 & 0 & 1 & | & -14/13 \end{bmatrix}
  6. Zero Out Third Column: Use the third row to zero out the rest of the third column:\newline- Subtract 77/33 times the third row from the first row.\newline- Subtract 11/33 times the third row from the second row.\newline[1003010500114/13] \begin{bmatrix} 1 & 0 & 0 & | & 3 \\ 0 & 1 & 0 & | & 5 \\ 0 & 0 & 1 & | & -14/13 \end{bmatrix}