Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 2 - Matrices and Systems of Linear Equations - 2.5 Gaussian Elimination - Problems - Page 166: 25

Answer

The solution is $(0,0,0)$

Work Step by Step

The augmented matrix of the system is: $\begin{bmatrix} 2&1 &-1 |0\\ 3 &-1 &2 | 0\\ 1& -1 & -1 |0\\ 5&2&-2 \end{bmatrix}$ with reduced row-echelon form: $\begin{bmatrix} 2&1 &-1 |0\\ 3 &-1 &2 | 0\\ 1& -1 & -1 |0\\ 5&2&-2 \end{bmatrix}\approx^1 \begin{bmatrix} 1&-1 &-1 |0\\ 2 &1 &-1 | 0\\ 1& -1 & -1 |0\\ 5&2&-2 \end{bmatrix} \approx^2 \begin{bmatrix} 1&-1 &-1 |0\\ 0 &2 &5 | 0\\ 0&3 & 1 |0\\ 0&7&3 \end{bmatrix} \approx^3 \begin{bmatrix} 1&-1 &-1 |0\\ 0 &3 &1 | 0\\ 0&2 & 5 |0\\ 0&7&3 \end{bmatrix} \approx^4 \begin{bmatrix} 1&-1 &-1 |0\\ 0 &1 &-4 | 0\\ 0&2 & 5 |0\\ 0&7&3 \end{bmatrix} \approx^5 \begin{bmatrix} 1&0 &-5 |0\\ 0 &1 &-4 | 0\\ 0&0 & 13 |0\\ 0&0&31 \end{bmatrix} \approx^6 \begin{bmatrix} 1&0 &-5 |0\\ 0 &1 &-4 | 0\\ 0&0 & 1 |0\\ 0&0&31 \end{bmatrix} \approx^7 \begin{bmatrix} 1&0 &0 |0\\ 0 &1 &0 | 0\\ 0&0 & 1 |0\\ 0&0&0 \end{bmatrix} $ $1.P_{13}$ $2.A_{12}(-3), A_{13}(-2),A_{14}(-5)$ $3.P_{13}$ $4.A_{32}(-1)$ $5.A_{21}(1),A_{23}(-2),A_{24}(-7)$ $6.M_3(\frac{1}{13})$ $5.A_{31}(5),A_{32}(4),A_{34}(-31)$ This matrix is now in row-echelon form. The solution set is: $x_1=0$ $x_2=0$ $x_3=0$ The solution is $(0,0,0)$
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