College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 5, Systems of Equations and Inequalities - Section 5.2 - Systems of Linear Equations in Several Variables - 5.2 Exercises - Page 455: 19

Answer

$x=1,$ $y=-1,$ $z=5$

Work Step by Step

$\begin{cases} x+2y-z=-6\\ 0x+y-3z=-16\\ x-3y+2z=14 \end{cases}$ Multiplying Equation 3 by -1 and adding it to Equation 1, results in new Equation 3. $\begin{cases} x+2y-z=-6\\ -x+3y-2z=-14\\ -- -- -- -- --\\ 5y-3z=-20 \end{cases}$ Multiplying Equation 2 by -5 and adding it to new Equation 3. $\begin{cases} -5y+15z=80\\ 5y-3z=-20\\ -- -- -- -- \\ 12z=60 \end{cases}$ Thus, $z=5$. Substituting back into Equation 2. $y-15=-16, y=-1$. Substituting back into Equation 1. $x-2-5=-6, x=1$.
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