Question

I need to find Domain and Range but how do I know when to use brackets or parentheses

Answer 1

Answer:

• Square brackets [ or ] are used when the end point is included.
• Parentheses ( or ) are used when the end point is not included.

Step-by-step 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]

_____

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.