Answer:
- Square brackets [ or ] are used when the end point is included.
- Parentheses ( or ) are used when the end point is not included.
Explanation:
The domain is the horizontal extent of the graph. Here, it is from -2 to +3, with -2 included in the domain and +3 not included.
As an inequality, the domain is written ...
-2 ≤ x < 3
In interval notation, we use a square bracket for the "or equal to" case:
[-2, 3)
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The range is the vertical extent of the function. Here, the range extends from -4 (not included) to +5 (included).
As an inequality, the range is written ...
-4 < y ≤ 5
In interval notation, the range is written using a square bracket for the "or equal to" case:
(-4, 5]
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Comment on infinity
There is no such thing as "equal to infinity" so an infinite limit is always represented in interval notation using a parenthesis.