# Interval notation

by science~life
Tags: interval, notation
 P: 2 Can anyone please give a succinct and clear description on this? I'm a little confused...
 Newcomer P: 341 I don't want to be a smartass, but look at http://en.wikipedia.org/wiki/Interval_%28mathematics%29 Can you specify why that link is not helpful, and what you don't understand?
 P: 448 http://www.purplemath.com/modules/setnotn.htm Set notation. This will help you read the wiki article. Need to know where you at with it to be able to help. Do you understand (a, b] means a isn't included in the interval but b is?
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P: 38,708

## Interval notation

(a, b) means "all numbers strictly between a and b". It can also be written as $\{x| a< x< b\}$.

[a, b) means "all numbers strictly between a and b and the number a. It can also be written as $\{x| a\le x< b\}$.

(a, b) means "all numbers strictly between a and b and the number b. It can also be written as $\{ x| a< x\le b\}$.

[a, b] means "all numbers strictlhy between a and b and both the number a and the number b. It can also be written as $\{x| a\le x\le b\}$.

In short, all of these contain the interval between a and b. "[" and "]" mean "include this end point". "(" and ")" mean "do not include this point".
P: 1,180
 Quote by HallsofIvy (a, b) means "all numbers strictly between a and b". It can also be written as $\{x| a< x< b\}$. [a, b) means "all numbers strictly between a and b and the number a. It can also be written as $\{x| a\le x< b\}$. (a, b) means "all numbers strictly between a and b and the number b. It can also be written as $\{ x| a< x\le b\}$. [a, b] means "all numbers strictlhy between a and b and both the number a and the number b. It can also be written as $\{x| a\le x\le b\}$. In short, all of these contain the interval between a and b. "[" and "]" mean "include this end point". "(" and ")" mean "do not include this point".
Third, HOI certainly means (a,b], just in case this is not caught.

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