Elementary Technical Mathematics

Published by Brooks Cole
ISBN 10: 1285199197
ISBN 13: 978-1-28519-919-1

Chapter 9 - Section 9.3 - Solving Pairs of Linear Equations by Substitution - Exercises - Page 334: 2



Work Step by Step

$3x+4y=-8$ $x=2y$ Using the value for x in the second equation, substitute 2y for x in the first equation. $3(2y)+4y=-8$ $\longrightarrow$ multiply $6y+4y=-8$ $\longrightarrow$ add $10y=-8$ $\longrightarrow$ divide both sides by 10 $10y\div10=-8\div10$ $\longrightarrow$ simplify $y=-\frac{4}{5}$ Substitute $-\frac{4}{5}$ for y in the second equation. $x=2(-\frac{4}{5})$ simplify $x=-1\frac{3}{5}$
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