In interval notation, what does a square bracket next to a number mean?
- That number is left out
- That number is included
- That number is negative
- That number is a limit
Show answer and solution
Correct answer: B. That number is included
1. Interval notation marks each end of a solution set with either a bracket or a parenthesis.
2. A bracket marks an endpoint that belongs to the set, matching a greater than or equal to sign.
3. A parenthesis marks an endpoint left out of the set, and infinity always takes a parenthesis.
_Source: OpenStax College Algebra (CC BY 4.0), section 2.7 Linear Inequalities and Absolute Value Inequalities_