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 6.5 - Page 652: 14

Answer

Solution set = $\{(-1,-3)\}$

Work Step by Step

$D= $determinant of the coefficient matrix $=\left|\begin{array}{ll} 1 & -2\\ 5 & -1 \end{array}\right|=1(-1)-(-2)(5)=9$ $D_{x}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 5 & -2\\ -2 & -1 \end{array}\right|=-5-4=-9$ $D_{y}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 1 & 5\\ 5 & -2 \end{array}\right|=-2-25=-27$ $x=\displaystyle \frac{D_{x}}{D}=\frac{-9}{9}=-1$ $y=\displaystyle \frac{D_{y}}{D}=\frac{-27}{9}=-3$ Solution set = $\{(-1,-3)\}$
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