# Math Help - Composition of Rational Functions

1. ## Composition of Rational Functions

I'm given:

If f(x) = $\frac{1}{x} - \frac{x}{4}$, then what is f( $\frac{1}{4x})$

what's the procedure for solving this? For f( $\frac{1}{4x})$, do I just divide 1 by 4 times $\frac{1}{x} - \frac{x}{4}$ ? I tried doing that and got the answer $\frac{x}{(2-x)(2+x)}$, but apparently that's not the answer. Can anyone work through this to show me the different stages of it?

2. ## Re: Composition of Rational Functions

in the formula of f(x) substitute every x with 1/4x.

Spoiler:
you should get: $f(x)=\frac{1}{\frac{1}{4x}}-\frac{\frac{1}{4x}}{4}=4x-\frac{1}{16x}$