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: 22

Answer

Solution set = $\{(1,-2)\}$

Work Step by Step

Rewrite the system: $\left\{\begin{array}{l} 4x+y=2\\ 2x-3y=8 \end{array}\right.$ $D= $determinant of the coefficient matrix $=\left|\begin{array}{ll} 4 & 1\\ 2 & -3 \end{array}\right|=4(-3)-(1)(2)=-14$ $D_{x}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 2 & 1\\ 8 & -3 \end{array}\right|=-6-8=-14$ $D_{y}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 4 & 2\\ 2 & 8 \end{array}\right|=32-4=28$ $x=\displaystyle \frac{D_{x}}{D}=\frac{-14}{-14}=1$ $y=\displaystyle \frac{D_{y}}{D}=\frac{28}{-14}=-2$ Solution set = $\{(1,-2)\}$
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