# Homework Help: Inverse of a function

1. Feb 7, 2010

### Kate2010

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

f(-1,+1) -> R is given by f(x) = x/(1 - |x|)

Find the inverse of f.

Are f and the inverse of f continuous?

2. Relevant equations

3. The attempt at a solution

I have shown that f is 1-1.
f((-1,+1)) -> (-$$\infty$$, +$$\infty$$)

Let y = f-1(x), so f(y) = x

y/ (1- |y|) = x
y = x(1- |y|)

If y = 0 x = 0
If y> 0 y =x(1-y), so y = x/(1+x)
If y< 0 y =x(1+y), so y = x/(1-x)

Can I say if y<0 then x <0 and if y >0 then x >0?
Then y=x/(1+|x|)

Would the domain of the inverse be (-$$\infty$$,+$$\infty$$)?

If this is so, f and the inverse of f are continuous as I know f(x) =x, f(x) = 1, f(x) = |x| are continuous and if f and g are continuous then so are |f|, f+g, f-g, and f/g.