Parentheses and/or brackets are used to show whether the endpoints are excluded or included. For example, [3, 8) is the interval of real numbers between 3 and 8, including 3 and excluding 8.

How do you know when to use brackets or parentheses interval notation?

Use interval notation to indicate all real numbers greater than or equal to −2 . Use a bracket on the left of −2 − 2 and parentheses after infinity: [−2,∞) [ − 2 , ∞ ) . The bracket indicates that −2 − 2 is included in the set with all real numbers greater than −2 − 2 to infinity.

Is interval notation always in parentheses?

Open and Closed Intervals

An open interval does not include its endpoints and is indicated with parentheses. ... For example, [0,1] describes an interval greater than or equal to 0 and less than or equal to 1. To indicate that only one endpoint of an interval is included in that set, both symbols will be used.