Physics Lab Uncertainties: Natural Log Method

[CINA]

Homework Statement

I'm doing a physics lab and need to do the uncertainties, and the method I'm using is the natural log method, hich goes like this:
(equation used was k*(x^a)*(y^b)*(z^c) )
http://img297.imageshack.us/img297/3663/lnform.jpg

The equation I'm doing:

http://img175.imageshack.us/img175/4214/40303282.jpg

I'm just wondering how it simplifies (the right most part of the first picture) so that I can take the partial dervs. (The Inside of ln is my actualy equation, calorimetry.)

Homework Equations

I don't know, otherwise I would apply them!

The Attempt at a Solution

It's a pretty straight foward problem, once I see it down once I think I can do it all the time in the future. The main problem I am having is dealing with the things in the denominator.

Thanks!

 

[CINA]

No one!? Is this not the correct approach? Would someone else use a different method to get an equation for the uncertainty?