Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 1 - Systems of Linear Equations - 1.1 Introduction to Systems of Linear Equations - 1.1 Exercises: 22

Answer

$x = 101$ $y = 96$ (101, 96)

Work Step by Step

$0.2x-0.5y=-27.8$ $0.3x+0.4y=68.7$ Multiply both sides of each equation by 10 so that you get: $2x - 5y = -278$ $3x + 4y = 687$ Express $x$ in terms of $y$ from the first equation: $2x = -278 + 5y$ $x = -139 + \frac{5}{2}y$ Substitute $x$ in the second equation: $3*(-139 + \frac{5}{2}y) + 4y = 687$ $-417 + \frac{15}{2}y + \frac{8}{2}y = 687$ $\frac{23}{2}y = 1104$ $23y = 2208$ $y = 96$ Substitute $y$ to get $x$ $2x-5*96=-278$ $2x=480-278$ $x=101$
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