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 - Page 10: 18

Answer

$x = 6$ $y = -3$ (6, -3)

Work Step by Step

$x-5y=21$ $6x+5y=21$ Add the equations. $x - 5y + (6x + 5y) = 21 + 21$ $x + 6x -5y + 5y = 42$ $7x = 42$ $x = 42/7$ $x = 6$ Substitute x in the first equation to get y $6 - 5y = 21$ $-5y = 15$ $y = -3$
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