- #1
pyrosilver
- 39
- 0
Homework Statement
For which numbers a, b, c, and d will the function
f(x) = (ax + b) / (cx + d)
satisfy f(f(x)) = x for all x (for which this equation makes sense)?
Homework Equations
The Attempt at a Solution
I'm not sure what to do, which is my problem. So far I think that I can plug in (ax + b) / (cx + d) for x, because that is when it will satisfy f(f(x)) = x, right?
So then I have:
http://img26.imageshack.us/img26/6364/mathnumber8.jpg
So I'm not sure where I want to end up, or where to go from here :( Can someone help me? This is due tomorrow. All help is appreciated.
Last edited by a moderator: