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: 22

Answer

$x=1,$ $y=-3,$ $z=2$

Work Step by Step

$\begin{cases} x+y+z=0\\ -x+2y+5z=3\\ 3x-y+0z=6 \end{cases}$ Adding Equation 1 and Equation 2, results in new Equation 2. $\begin{cases} x+y+z=0\\ -x+2y+5z=3\\ -- -- -- -- --\\ 3y+6z=3 \end{cases}$ Multiplying Equation 1 by -3 and Adding it to Equation 3, results in new Equation 3. $\begin{cases} -3x-3y-3z=0\\ 3x-y+0z=6\\ -- -- -- -- --\\ -4y-3z=6 \end{cases}$ Multiplying new Equation 3 by 2 and Adding it to new Equation 2. $\begin{cases} -8y-6z=12\\ 3y+6z=3\\ -- -- -- --\\ -5y=15 \end{cases}$ Thus, $y=-3$. Substituting back into Equation 3, $3x+3=6, x=1$. Substituting back into Equation 1, $1-3+z=0, z=2$.
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