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 165: 3

Answer

$x_1=\frac{5+3t}{7}$ $x_2=t$

Work Step by Step

The augmented matrix of the system is: $\begin{bmatrix} 7& -3 |5\\ 14 & -6| 10 \end{bmatrix}$ with reduced row-echelon form: $\begin{bmatrix} 7& -3 |5\\ 14 & -6| 10 \end{bmatrix}\approx^1\begin{bmatrix} 7& -3 |5\\ 0 & 0| 0 \end{bmatrix} \approx^2\begin{bmatrix} 1& -\frac{3}{7} |\frac{5}{7}\\ 0 & 0| 0 \end{bmatrix}$ The equivalent system is: $7x_1-3x_2=5$ Since $x_2$ does not occur in the system, it is a free variable and therefore not necessarily zero: $x_2=t$ $7x_1-3t=5 \rightarrow x_1=\frac{5+3t}{7}$
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