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: 21

Answer

Solution set = $\{(7,4)\}$

Work Step by Step

Rewrite the system: $\left\{\begin{array}{l} 2x-3y=2\\ 5x+4y=51 \end{array}\right.$ $D= $determinant of the coefficient matrix $=\left|\begin{array}{ll} 2 & -3\\ 5 & 4 \end{array}\right|=2(4)-(-3)(5)=23$ $D_{x}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 2 & -3\\ 51 & 4 \end{array}\right|=8+153=161$ $D_{y}=$ in D, replace the x column with the constants column $=\left|\begin{array}{ll} 2 & 2\\ 5 & 51 \end{array}\right|=102-10=92$ $x=\displaystyle \frac{D_{x}}{D}=\frac{161}{23}=7$ $y=\displaystyle \frac{D_{y}}{D}=\frac{92}{23}=4$ Solution set = $\{(7,4)\}$
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