Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter P - Section P.9 - Linear Inequalities and Absolute Value Inequalities - Exercise Set - Page 138: 38


The solution set is $(-\infty, -4)$.

Work Step by Step

The idea is to isolate x on one side. Adding, subtracting or multiplying/dividing with a positive number preserves order (the inequality symbol remains). Multiplying/dividing with a negative number inverts the order (the inequality symbol changes). --- $-4(x+2) \gt 3x+20\qquad $ ... distribute, simplify $-4x-8 \gt 3x+20\qquad $ ... $/-3x+8$ $-7x \gt 28 \qquad $ ... $/\div(-7) \quad $ (negative) $ x \lt -4$ The solution set is $(-\infty, -4)$ .
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