# Homework Help: Need help on how to prove a function is odd.

1. Aug 16, 2014

### DennyCrane

I need to prove f(x)=x/x^2+1

I'm not sure how to because I never do this with fractions and it's just messed me up. Any help is appreciated.

2. Aug 16, 2014

### Staff: Mentor

Welcome to PF!

THis looks like homework and we have forum rules that it must be submitted using the homework template. If you look at other posts you should see how its done.

Next:

DId you write the equation correctly is it?

f(x) = (x/x^2) + 1

or is it?

f(x) = x / (x^2 + 1)

I think you meant the 2nd one, right?

Now:

What is the definition of an odd function?

3. Aug 16, 2014

### SteamKing

Staff Emeritus
IDK why the particular form of this function is tripping you up.

To prove f(x) is odd, you must show is that -f(x) = f(-x), for all x and -x in the domain of f.

http://en.wikipedia.org/wiki/Even_and_odd_functions

What happens when you evaluate f(-x) for this function?

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