Composite Functions

do you mean convolution?

No, I am pretty sure fd means composition of functions (convolution requires calculus).

fd,

You are trying to find
f( x/(x-1))

The easiest way to think of this is make two copies of the function and force yourself to think of it as two different functions (the confusion is that they still look the same).

so the first function is

x/(x-1)

and the second function is

x/(x-1)

Now take the first function and whereever you see an x, replace that "x" by the second function. So this would be

(x/(x-1)/((x/(x-1) -1)

[take the time to understand what I just did. It is really important.]

It will help if you write this expression on a piece of paper with big lines for the division sign instead of this damn computer stuff.

Now all you have to do is simplify.

If you take a shot at it, I would be happy to give you feedback.

ok
First of all, what is convolution? Is this a first-year calculus topic? My question is a simple composite function at the pre-calculus level. I want to thank ebrown_p for your quick reply.

Ok. Convolution is a 4th year calculus topic, it uses the * symbol notation.

hey
Thanks. I will not see it for some time.

http://mathworld.wolfram.com/Convolution.html

Whereas composition is like recursion in Computing Science (not the maths version) - ugh nightmares of 2nd year Uni!

I always found it easy to two step it and use round and square brackets, like:

x/(x-1) , write it as [K] / ( [K] - 1)

Now take the first function and wherever you see an [K], replace it by your function. So this would be

[x/(x-1)] /( [x/(x-1)] -1)

Helps you to visualise it a bit easier maybe?