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: 20

Answer

The solution set is $(-5t,-1-2t,t)$

Work Step by Step

$Ax=b$ $\begin{bmatrix} 1 & 0 & 5\\ 3 & -2 & 11\\ 2 & -2 &6 \end{bmatrix}.\begin{bmatrix} x_1\\ x_2\\ x_3 \end{bmatrix}=\begin{bmatrix} 0\\ 2\\ 2 \end{bmatrix}$ 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 & 0 & 5|0\\ 3 & -2 & 11|2\\ 2 & -2 &6|2 \end{bmatrix} \approx^1 \begin{bmatrix} 1 & 0 & 5|0\\ 0 & -2 & -4|2\\ 0 & -2 &-4|2 \end{bmatrix} \approx^2 \begin{bmatrix} 1 & 0 & 5|0\\ 0 &1 & 2|-1\\ 0 & -2 &-4|2 \end{bmatrix} \approx^3\begin{bmatrix} 1 & 0 & 5|0\\ 0 &1 & 2|-1\\ 0 & 0 &0|0 \end{bmatrix} $ 1. $A_{12}(-3),A_{13}(-2)$ 2. $M_2(\frac{-1}{2})$ 5. $A_{23}(2)$ The equivalent system is $x_1+5x_3=0$ $x_2+2x_3=-1$ $x_3 = t$ There is one free variable, which we take to be $x_3 = t$, where t can assume any complex value. Applying back substitution yields: $x_3 = t$ $x_2+2t=-1 \rightarrow x_2=-1-2t$ $x_1+5t=0 \rightarrow x_1=-5t$ The solution set is $(-5t,-1-2t,t)$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.