# What are the domain and range of this relation

1. Dec 13, 2011

### checkitagain

in interval notation?

$y^2(x^2 - 1) = x^4$

(This is my own problem.)

2. Dec 13, 2011

### Staff: Mentor

Do you know the definition of Domain and Range of a function? Can you tell us what you think they are?

Then, is there anything that would inherently limit the domain of the function?

EDIT -- BTW, you haven't really defined a function yet. Domain and Range generally apply to a function...

3. Dec 13, 2011

### Staff: Mentor

If you put the relation into the form y = f(x), then you can talk about the Domain and Range of that function...

4. Dec 13, 2011

### Staff: Mentor

Your equation is equivalent to
$$y^2 = \frac{x^4}{x^2 - 1}$$
From this, you can solve for y.

5. Dec 13, 2011

### checkitagain

I am not trying to define a function. I know this is a relation
that is not a function.

And relations can have domains and ranges, as this one does.

In this problem I am challenging others with, I expect others to know
what the domain and range mean, but those aren't questions for me
in this particular problem.

One of many sources:

http://www.purplemath.com/modules/fcns2.htm

This relation can't be put into into a form y = f(x), because it isn't
a function to begin with.

6. Dec 13, 2011

### checkitagain

No, I am testing (read: challenging) users' knowledge
of domain and range to figure them out of this relation,
whether in my form or the equivalent form given by
Mark44.

I will be on at least a 90-minute break before returning

7. Dec 13, 2011

### Staff: Mentor

It would have been helpful to include that information in your first post.

And that brings up a question: Since this isn't a question for you, why did you post it?

8. Dec 13, 2011

### micromass

Since this is just testing of our knowledge, this means that this isn't a valid homework problem. So the thread can be locked.