Math Is Fun Forum

nycguitarguy

Member

Registered: 2024-02-24

Posts: 553

Points As Function Relationship

Determine if each relation is a function. For each function, state the domain and range.

Question 1

{(-2, 5), (-1, 3), (3, 7), (4, 12)}

Here, no x-value has 2 different values of y.
I say this is a ffunction.

Domain = values of x

Range = values of y

Do you agree?

Question 2

{(-4, 4), (-3, 3), (-2, 2), (-1, 1), -4, 0)}

I say this is not a function because -4 has two different values of y.

You say?

amnkb

Member

Registered: 2023-09-19

Posts: 253

Re: Points As Function Relationship

1. agree that its a fcn

2. agree

nycguitarguy

Member

Registered: 2024-02-24

Posts: 553

Re: Points As Function Relationship

1. agree that its a fcn

2. agree

For the domain,  we can also say x-values.

For the range, we can also say y-values.

Look here: (x, y) = (domain, range)

Agree?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,199

Re: Points As Function Relationship

I understand why you might say that.  There are some maths courses out there that agree with this idea.

But, according to Wolfram Alpha, domain is defined as "the set of values for the independent variable for which a functioin is defined".  x has only been given for a limited set of values so that fixes the domain as {-2, -1, 3, 4}.  Range is similarly defined.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

nycguitarguy

Member

Registered: 2024-02-24

Posts: 553

Re: Points As Function Relationship

I understand why you might say that.  There are some maths courses out there that agree with this idea.

But, according to Wolfram Alpha, domain is defined as "the set of values for the independent variable for which a functioin is defined".  x has only been given for a limited set of values so that fixes the domain as {-2, -1, 3, 4}.  Range is similarly defined.

Bob

To me, domain = x and range = y. It's easier to think about it this way.