Introduction to Interval Notation

a method used to represent a set of real numbers between two intervals

Define Interval Notation

a set of brackets

Endpoints are listed within?

Closed intervals (intervals that include both endpoints)

Square brackets [] indicate what type of interval?

Open intervals (intervals that do not include either endpoint)

Rounded brackets () indicate what type of interval?

With one square bracket and one rounded bracket

How is a half-closed or half-open interval indicated?

∞ with a rounded bracket

How is the upper endpoint written for sets with no upper boundary?

−∞ with a rounded bracket

How is the lower endpoint written for sets with no lower boundary?

The number is part of the interval

On a number line, what does a solid dot mean?

The number is not part of the interval

On a number line, what does an open dot mean?

With rounded brackets (since they are not defined endpoints)

How are −∞ or ∞ always listed in interval notation?

Belongs to

What does the symbol ∈ mean?