Finite Math and Applied Calculus (6th Edition)

Published by Brooks Cole
ISBN 10: 1133607705
ISBN 13: 978-1-13360-770-0

Chapter 3 - Section 3.2 - Using Matrices to Solve Systems of Equations - Exercises - Page 204: 9

Answer

$(\displaystyle \frac{1}{4},\frac{3}{4})$

Work Step by Step

Write the augmented matrix and, using row transformations arrive at the reduced row echelon form (rref). ----------- $\left[\begin{array}{lll} 1 & 1 & 1\\ 3 & -1 & 0\\ 1 & -3 & -2 \end{array}\right]\begin{array}{l} .\\ R_{2}-3R_{1}.\\ R_{3}-R_{1}. \end{array}$, clear column $1$ $\left[\begin{array}{lll} 1 & 1 & 1\\ 0 & -4 & -3\\ 0 & -4 & -3 \end{array}\right]\begin{array}{l} .\\ .\\ R_{3}-R_{2}. \end{array}$, clear column 2$...$ $\left[\begin{array}{lll} 1 & 1 & 1\\ 0 & -4 & -3\\ 0 & 0 & 0 \end{array}\right]\begin{array}{l} .\\ -\frac{1}{4}R_{1}.\\ . \end{array}$, leading 1 in row 2 $\left[\begin{array}{lll} 1 & 1 & 1\\ 0 & 1 & 3/4\\ 0 & 0 & 0 \end{array}\right]\begin{array}{l} R_{1}-R_{2}.\\ .\\ . \end{array}$, clear column 2 $\left[\begin{array}{lll} 1 & 0 & 1/4\\ 0 & 1 & 3/4\\ 0 & 0 & 0 \end{array}\right]$ System is consistent (last row has all zeros) $x=1/4$ $y=3/4$ Solution: $(\displaystyle \frac{1}{4},\frac{3}{4})$
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