I am evaluating the function

The derivative should be

I am trying to find the critical numbers:

Here comes my problem... I used two different methods but my results are different

Method one:

(common denominator)

And so on...

Method two:

And so on...

When I nowcompare method one with method twoI see thatisdifferentfrom. (Why is my result in method two not devided by x?)

My question is now, why? And what am I doing wrong? :/

Please help