Bufo is correct, the chain rule and the product rule are what you need here to differentiate. Although you could show from inspection that because the expression is composed of powers of the factors (2x-1) and (x-2) the differential will also have these factors so for dy/dx=0 one of these factors has to be 0, ie. 2x-1=0 or x-2=0 which is where you get x=1/2 or x=2. I'd avoid these kind of arguments in assigments though as they are usually looking for all the steps in the process. I'm more than happy to help with other questions you have, although it looks like you're well covered here!
I often recommend this site to people in need of Math help. http://www.khanacademy.org/#calculus Scroll down to the list of different sub-subjects in the Calculus section and watch the videos on Differentiation. Very easy to follow step by step on how it all works.
I very briefly understand both rules as i used them earlier on i think its the question thats tripping me up. I think i've got it all wrapped up now mate i know im probebly the furthest ahead with the assignement purely because i've spent the entire week doing it and making sure i've done as much as possible. Its easy to get help all they way through but its important for me to be able to understand the answer aswell as the question theres a few just getting others to do it which is all fine until the exam when they have to do it for themselves, the few i've asked about luckily i've learnt from and now understand thanks to the great bit-tech!. Anything i can't do now i will leave as its in for tommorow im sure he will give us more time once he realizes how much we have struggled if not im sure i've done well! (atleast i hope i have) Thanks mate! i'll give that a look and a bookmark Revision soon so im sure it will come in handy
