Precalculus (6th Edition)

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

Chapter 1 - Equations and Inequalities - 1.7 Inequalities - 1.7 Exercises: 11

Answer

A parenthesis is used when the number beside it is not included in the set, while a square bracket is used when the number is included in the set. Refer to the examples and explanation below.

Work Step by Step

A parenthesis will be used when the number that serves as a boundary (either lower or upper boundary) is not included in the set. A square bracket will be used when the number that serves as a boundary (either lower or upper boundary) is included in the set. Examples: (1) $(3, 9)$ means 3 and 9 are not included in the set (2) $(3, 9]$ means 3 is not included but 9 is included in the set (3) $[3, 9]$ means both 3 and 9 are included in the set
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