Difference between revisions of "Interval"

Revision as of 22:12, 16 August 2013

An interval is a range of values. The most common uses of an interval are for domain and range.

If an interval has either $($ or $)$ in it, the values at the end are NOT included in the interval.

If an interval has either $[$ or $]$ in it, the values at the end ARE included.

If both endpoints are not included, then the interval is open. If both endpoints are included, then the interval is closed.

Note: The symbols $($ and $)$ are used with $-\infty$ and $\infty,$ by convention

$(2,3)$ means all real numbers between $2$ and $3,$ but not including $2$ or $3.$

$[-2,0)$ means all real numbers between $-2$ and $0,$ including $-2,$ but not including $0.$

@@ Line 7: / Line 7: @@
 If an interval has either <math>(</math> or <math>)</math> in it, the values at the end are '''NOT''' included in the interval.
-If an interval has either <math>[</math> or <math>]</math> in it, the values at the end '''ARE''' included. For example, the interval <math>x \in [2.5,7]</math> refers to the inequality <math>2.5 \le x \le 7.</math>
+If an interval has either <math>[</math> or <math>]</math> in it, the values at the end '''ARE''' included.
 If both endpoints are not included, then the interval is '''open.''' If both endpoints are included, then the interval is '''closed.'''
-''Note'': The symbols <math>(</math> and <math>)</math> are used with <math>-\infty</math> and <math>\infty.</math>
+''Note'': The symbols <math>(</math> and <math>)</math> are used with <math>-\infty</math> and <math>\infty,</math> by convention
 == Examples ==