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: 19

Answer

The solution set is $(1,-3,-2)$

Work Step by Step

$Ax=b$ $\begin{bmatrix} 1 & -3 & 1\\ 5 & -4 & 1\\ 2 & 4 &-3 \end{bmatrix}.\begin{bmatrix} x_1\\ x_2\\ x_3 \end{bmatrix}=\begin{bmatrix} 8\\ 15\\ -4 \end{bmatrix}$ Converting the given system of equations to an augmented matrix and then using Gauss-Jordan elimination to determine the solution set to the given system. $\begin{bmatrix} 1 & -3 & 1|8\\ 5 & -4 & 1|15\\ 2 & 4 &-3|-4 \end{bmatrix} \approx^1 \begin{bmatrix} 1 & -3 & 1|8\\ 0& 11 &-4|15\\ 0 & 10 &-5|-4 \end{bmatrix} \approx^2 \begin{bmatrix} 1 & -3 & 1|8\\ 0& 1 &1|-5\\ 0 & 10 &-5|-4 \end{bmatrix} \approx^3 \begin{bmatrix} 1 & 0 & 4|-7\\ 0& 1 &1|-5\\ 0 & 0 &-15|30 \end{bmatrix} \approx^4 \begin{bmatrix} 1 & 0 & 4|-7\\ 0& 1 &1|-5\\ 0 & 0 &1|-2 \end{bmatrix} \approx^5 \begin{bmatrix} 1 & 0 & 0|1\\ 0& 1 &0|-3\\ 0 & 0 &1|-2 \end{bmatrix}$ 1. $A_{12}(-5),A_{13}(-2)$ 2. $A_{32}(-1)$ 3. $A_{21}(3), A_{23}(-10)$ 4. $M_3(\frac{-1}{15})$ 5. $A_{31}(-4),A_{32}(-1)$ The solution set is $(1,-3,-2)$
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