# Simplifying Derivative

1. Jan 24, 2010

### Whiz

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

Let f(x) = sqrt(4-x2) + 2cos-1(x/2)

Then f '(x) can be written in simplified form -[(x+c)/(mx+n)]p
NOTE: I'm not sure if that negative is supposed to be there since my book is smudged.

What are the values of c, m, n, and p?

2. Relevant equations

Derivative of cos-1(x) is -1/(sqrt(1-x2)

3. The attempt at a solution

I found the derivative to be -x/sqrt(4-x2) - 1/sqrt(1-(x/2)2)

My problem is that I have no idea how to simplify it into that form. Can anyone offer me some assistance on this question?

Try multiplying $$-\frac{1}{\sqrt{1-(\frac{x}{2})^{2}}}\cdot\frac{2}{2}$$