Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 3 Linear Systems and Matrices - 3.4 Solve Systems of Linear Equations in Three Variables - 3.4 Exercises - Skill Practice - Page 182: 9

Answer

$x=1$ $y=5$ $z=6$

Work Step by Step

Using elimination for the first two equations: $3x + y + z = 14$ $-x + 2y - 3z =-9$ Multiply both sides of the first equation by $-2$: $-6x -2 y -2 z = -28$ $-x + 2y - 3z =-9$ __________________________ $-7x-5z=-37$ (1) Then continue to use elimination for the first and third equations: $3x + y + z = 14$ $5x-y+5z=30$ _____________________ $8x+6z=44$ (2) From (1) and (2): $-7x-5z=-37$ $8x+6z=44$ Multiply both sides of the first equation by $8$ and the second equation by $7$: $-56x-40z=-296$ $56x+42z=308$ _________________________ $2z=12$ $z=6$ Solve for x: $8x+6(6)=44$ $8x=8$ $x=1$ Solve for y: $3(1) + y + 6 = 14$ $y=5$
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