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 168: 43

Answer

The solution $(0,0,0)$

Work Step by Step

The augmented matrix of the system is: $\begin{bmatrix} 1&-1 &1 |0\\ 0&3 &2 |0\\ 3&0 &-1 | 0 \\ 5 &1 &-1|0 \end{bmatrix}$ with reduced row-echelon form: $\begin{bmatrix} 1&-1 &1 |0\\ 0&3 &2 |0\\ 3&0 &-1 | 0 \\ 5 &1 &-1|0 \end{bmatrix} \approx^1 \begin{bmatrix} 1&-1 &1 |0\\ 0&3 &2 |0\\ 0&3 &-4 | 0 \\ 0 &6 &-6|0 \end{bmatrix} \approx^2 \begin{bmatrix} 1&-1 &1 |0\\ 0&1 &\frac{2}{3} |0\\ 0&3 &-4 | 0 \\ 0 &6 &-6|0 \end{bmatrix} \approx^3 \begin{bmatrix} 1&0 &\frac{5}{3} |0\\ 0&1 &\frac{2}{3} |0\\ 0&0 &-6 | 0 \\ 0 &0 &-10|0 \end{bmatrix} \approx^4 \begin{bmatrix} 1&0 &\frac{5}{3} |0\\ 0&1 &\frac{2}{3} |0\\ 0&0 &1| 0 \\ 0 &0 &-10|0 \end{bmatrix} \approx^5\begin{bmatrix} 1&0 &0 |0\\ 0&1 &0|0\\ 0&0 &1| 0 \\ 0 &0 &0|0 \end{bmatrix}$ $1.A_{13}(-3),A_{14}(-5)$ $2.M_2(\frac{1}{3})$ $3.A_{21}(1),A_{23}(-3),A_{24}(-6)$ $4.M_3(-\frac{1}{6})$ $5.A_{31}(-\frac{5}{3}),A_{32}(-\frac{2}{3}),A_{34}(10)$ This matrix is now in row-echelon form. The solution set is: $x_1=0$ $x_2=0$ $x_3=0$ Hence, the solution is $(0,0,0)$
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