Question

How do you find the domain and range and determine whether the relation is a function given {(-2.5,1), (-1,-1), (0,1), (-1,1)}?

Answer 1

Domain: `{-2.5, -1, 0}`

Range: `{-1, 1}`

This relation is NOT a function.

Explanation:

The domain is also known as the `x`-values and the range is the `y`-values.

Since we know that a coordinate is written in the form `(x, y)`, the `x`-values are:
`{-2.5, -1, 0, -1}`

However, when we write a domain or range, we typically put the values from least to greatest and do not repeat numbers. Therefore, the domain is:
`{-2.5, -1, 0}`

All the `y`-values are:
`{1, -1, 1, 1}`

Again, put them from least to greatest and do not repeat numbers:
`{-1, 1}`

In a function, each `x`-value can only pair with one `y`-value (each input has a single output). Since there are two `-1`s in the `x`-values pairing with different `y`-values, this relation is NOT a function.

Hope this helps!