Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 10 - Systems of Equations and Inequalities - Section 10.1 Systems of Linear Equations: Substitution and Elimination - 10.1 Assess Your Understanding - Page 734: 41

Answer

$x=8; y=2; z=0$ or, $(8,2,0)$

Work Step by Step

We need to solve the given system of equations: $$x-y=6 ~~~~ ( 1)\\ 2x-3z=16 ~~~(2) \\ 2y+z=4 ~~~~(3)$$ First, we will multiply equation $(3)$ by $3$ to get: $$ 6y+3z=12\quad \quad(4)$$ Now, add equations $(2)$ and $(4)$ to obtain: $$2x-3z+6y+3z=16+12\\ 2x+6y=28 ~~~~(5)$$ In order to solve for $x$, we will multiply equation $(1)$ by $6$ and then add the new equation and equation $(5)$ to get: $$6x-6y+2x+6y=36+28 \\ 8x =64 \\ x=8$$ Now, back substitute $x$ into Equation $(1)$ to solve for $y$: $$8-y=6 \\ y=8-6 \\ y=2$$ Finally, back substitute $y$ into Equation $(3)$ to solve for $z$: $$(2)(2)+z=4 \\ 4+z=4 \\ z=4-4 \\ z=0$$ So, the solution is $x=8; y=2; z=0$ or, $(8,2,0)$
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