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 735: 54

Answer

$x=3; y=-\dfrac{8}{3}; z=\dfrac{1}{9}$

Work Step by Step

We need to solve the given system of equations: $x+4y-3z=-8 ~~(1)\\ 3x-y+3z=12~~(2) \\ x+y+6z=1~~(3)$ First, we will add equation (2) and equation (3) to eliminate $y$. So, we get: $4x+9z=13~~(4)$ Now, multiply equation (2) by $4$ and add it to equation (1) to eliminate $y$. So, we get: $13x+9z=40~~(5)$ Now, simplify equations (4) and (5) to solve $x$ and $z$. $-4x+13x=13+40 \implies x=3$ Back substitute the value of $z$ into Equation (4) to solve for $y$: $(4)(3)+9z=13 \implies z=\dfrac{1}{9}$ Finally, back substitute the values of $x, z$ into Equation (3) to solve for $y$: $3+y+(6)(\dfrac{1}{9})=1 \implies y=-\dfrac{8}{3}$ So, $x=3; y=-\dfrac{8}{3}; z=\dfrac{1}{9}$
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