## Precalculus (6th Edition)

Published by Pearson

# Chapter 9 - Systems and Matrices - 9.1 Systems of Linear Equations - 9.1 Exercises: 23

#### Answer

$\{(4,-2)\}$

#### Work Step by Step

1. The least work in creating opposite coefficients is to multiply the first equation by ($-2)$ , which will lead to eliminating $x:$ $\left\{\begin{array}{lll} -10x & -14y & =-12\\ 10x & -3y & =46 \end{array}\right.$ 2. ... add the equations and solve $-17y=34\qquad/\div(-17)$ $y=-2$ 3. Back-substitute into one of the initial equations $5x+7y=6$ $5x+7(-2)=6$ $5x-14=6\qquad/+14$ $5x=20\qquad/\div 5$ $x=4$ 4. Write the solution as an ordered pair. Solution set: $\{(4,-2)\}$

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