Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Section 10.3 - Matrices and Systems of Linear Equations - 10.3 Exercises - Page 710: 49

Answer

$(-2,1,3)$

Work Step by Step

Write the augmented matrix and, using row transformations, arrive at the row-reduced echelon form. $\left[\begin{array}{llll} 4 & -3 & 1 & -8\\ -2 & 1 & -3 & -4\\ 1 & -1 & 2 & 3 \end{array}\right]\ \ \begin{array}{l} R_{1}\leftrightarrow R_{3}.\\ .\\ . \end{array}$ $\left[\begin{array}{llll} 1 & -1 & 2 & 3\\ -2 & 1 & -3 & -4\\ 4 & -3 & 1 & -8 \end{array}\right]\ \ \begin{array}{l} .\\ +2R_{1}.\\ -4R_{1}. \end{array}$ $\left[\begin{array}{llll} 1 & -1 & 2 & 3\\ 0 & -1 & 1 & 2\\ 0 & 1 & -7 & -20 \end{array}\right]\ \ \begin{array}{l} -R_{1}.\\ \times(-1).\\ +R_{2}. \end{array}$ $\left[\begin{array}{llll} 1 & 0 & 1 & 1\\ 0 & 1 & -1 & -2\\ 0 & 0 & -6 & -18 \end{array}\right]\ \ \begin{array}{l} .\\ .\\ \div(-6). \end{array}$ $\left[\begin{array}{llll} 1 & 0 & 1 & 1\\ 0 & 1 & -1 & -2\\ 0 & 0 & 1 & 3 \end{array}\right]\ \ \begin{array}{l} -R_{3}.\\ .+R_{3}\\ . \end{array}$ $\left[\begin{array}{llll} 1 & 0 & 0 & -2\\ 0 & 1 & 0 & 1\\ 0 & 0 & 1 & 3 \end{array}\right]$ Solution: $(-2,1,3)$
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