We can use interval notation to show that a value falls between two endpoints. ... For example, -3≤x≤2, [-3,2], and {x∈ℝ|-3≤x≤2} all mean that x is between -3 and 2 and could be either endpoint.

What does the interval (- ∞ ∞ indicate?

Notice the symbol ∞ which mean infinity. -∞ means minus infinity and +∞ means positive infinity. Both -∞ and +∞ are used to show that an interval is unbounded or extends indefinitely to the left or to the right respectively.

How do you write infinity in interval notation?

Using Interval Notation

For infinite intervals, use Inf for ∞ (infinity) and/or -Inf for -∞ (-Infinity). For example, the infinite interval containing all points greater than or equal to 6 is expressed [6,Inf).