Interval Notation: Clear Explanation

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    Interval Notation
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Interval notation is a mathematical way to describe sets of numbers within a specific range. The symbols "[" and "]" indicate that an endpoint is included in the interval, while "(" and ")" indicate that an endpoint is excluded. For example, (a, b) includes all numbers strictly between a and b, while [a, b] includes both endpoints. The notation can also be expressed using set-builder notation, such as {x | a < x < b}. Understanding these distinctions is crucial for interpreting and using interval notation effectively.
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Can anyone please give a succinct and clear description on this? I'm a little confused...
 
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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?
 
(a, b) means "all numbers strictly between a and b". It can also be written as \{x| a&lt; x&lt; 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&lt; b\}.

(a, b) means "all numbers strictly between a and b and the number b. It can also be written as \{ x| a&lt; 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".
 
HallsofIvy said:
(a, b) means "all numbers strictly between a and b". It can also be written as \{x| a&lt; x&lt; 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&lt; b\}.

(a, b) means "all numbers strictly between a and b and the number b. It can also be written as \{ x| a&lt; 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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