Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - 9.1 Systems of Linear Equations - 9.1 Exercises - Page 856: 1

Answer

4

Work Step by Step

Given that we know x=1 is part of the solution set, we back-substitute it into one of the initial equations: $x+y=5$ $1+y=5\quad/-1$ $y=4$ Confirm by substituting into the first equation: $-2(1)+5(4)=18$
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