# F composed of f

1. Sep 14, 2014

### najatau

1. The problem statement, all variables and given/known data

Find f°f

2. Relevant equations

f(x)=x/x+1

3. The attempt at a solution

$$\frac{x}{x+1}$$ divided by $$\frac{x}{x+1}$$ I got $$\frac{1}{x+1}+1$$ but I know the answer in the book is $$\frac{x}{2x+1}$$. I'm not sure how the book arrived at that answer.

Last edited by a moderator: Sep 17, 2014
2. Sep 14, 2014

### Staff: Mentor

How did you get your result?

3. Sep 14, 2014

### vela

Staff Emeritus
You mean f(x) = x/(x+1), right? Because what you wrote simplifies to f(x)=2 for x≠0.

Are X and x supposed to be the same variable? If not, what's X? If they're supposed to be the same, use the same letter.

How did you come up with that division? Please explain what you're doing in more detail.

4. Sep 14, 2014

### najatau

Thanks for responding. I just found out why I got the wrong answer. I wasn't dividing complex/compound fractions with monomials in the denominator correctly. I tried to multiply the numerator by the reciprocal of the denominator instead of finding the lowest common denominator for the numerator and denominator like I saw in this video.

I got the book's answer when I did it the way the video instructed. Not sure why I didn't get the same answer either way.
(:-/

Last edited by a moderator: Sep 25, 2014