## gandalfwiz 4 years ago Can someone explain "domain" and "range"? (When talking about functions

1. Zxen

"Domain" is the set of all possible inputs. Any values that don't give you a nonexistent answer (division by 0, etc) when you plug them into the function. "Range" is the set of all possible outputs. Hope this helps!

2. gandalfwiz

could u explain a bit further... thanks :)

3. Hero

domain - the set of x "input" values of a function that produces a valid y range - the y "output" values that correspond with given set of x values

4. Zxen

Sure! What are you confused about? :)

5. gandalfwiz

OH thanks Hero! And Zxen too:)

6. Hero

You're welcome

7. gandalfwiz

do you have to have more than one x,y point to have a function?

8. Hero

I don't think a point by itself can represent a function....Well, I've never seen it....you would normally write f(x) normally represents some expression in terms of x, so it would have a certain amount of inputs and outputs. Can you write a point in the form of an expression? I don't think so.

9. Zxen

Nope. Most functions have more than one, but as long as each x value corresponds to one and only one y-value, it's a function. :) Do you have a particular problem you need help with, or is this just general stuff?

10. Hero

So from my point of view, I'd say you can't represent a point as f(x). That being said, you can restrict values of x in a function.

11. gandalfwiz

new school, new math course :P Want to see if I can do most of the problems by myself though. Those were just some terms that tripped me up.

12. gandalfwiz

logging off and returning to my books %0 Thanks guys!

13. Zxen

Anytime! :D

14. polpak

You can have a function of only one point. A function is just a relational mapping of input values and output values where each input value is mapped to one (and only one) output value. So for example the function: $f_1(x) = \cases{\begin{array}{ccc}4 & \text{if} & x = 1\end{array}}$ Would be an example of a function which has only one element in its domain: {1} and only one element in its range: {4}. If you were to graph this function you'd just have that one point. Since each element in the domain maps to only one element in the range, the relation satisfies the requirements of a function.