College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 6 - Matrices and Determinants - Exercise Set 6.2 - Page 609: 18

Answer

Solution set: $\{ ( -2t+3$ , $-2t+1$ , $t )$ , $t\in \mathbb{R}\}$

Work Step by Step

Augmented matrix: $\left[\begin{array}{lllll} 3 & -1 & 4 & | & 8\\ 0 & 1 & 2 & | & 1 \end{array}\right]\left\{\begin{array}{l} \div 3\\ . \end{array}\right.$ $\left[\begin{array}{lllll} 1 & -1/3 & 4/3 & | & 8/3\\ 0 & 1 & 2 & | & 1 \end{array}\right]$ The system is consistent and does not have a unique solution. Let $z=t, t\in \mathbb{R}$. Substituting into row 2, $y+2t=1$ $y=-2t+1$ Substituting into row 1, $x-\displaystyle \frac{1}{3}(-2t+1)+\frac{4}{3}t=\frac{8}{3}$ $x+\displaystyle \frac{6}{3}t-\frac{1}{3}=\frac{8}{3}$ $x=-2t+\displaystyle \frac{8}{3}+\frac{1}{3}$ $x=-2t+3$ Solution set: $\{ ( -2t+3$ , $-2t+1$ , $t )$ , $t\in \mathbb{R}\}$
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