I need some help on a quotient derivative:

$\displaystyle \frac{a+\sqrt{x}}{a-\sqrt{x}}$

Here is what I have so far:

1. $\displaystyle \frac{(a-x^{1/2})(\frac{1}{2}x^{-1/2}) - (a+x^{1/2})(\frac{-1}{2}x^{-1/2})}{(a-\sqrt{x})^2}$

2. $\displaystyle \frac{\frac{1}{2} ax^\frac{-1}{2} - \frac{1}{2}x^0 +\frac{1}{2} ax^\frac{-1}{2}- \frac{1}{2}x^0}{(a-\sqrt{x})^2} $

I know my algebra must be wrong because I'm coming up with a totally different answer than the book. Could someone please help give me a play by play?

Thanks

-db