Tricky (for me anyway) Differentiation.

Hi

I am trying to differentiate.

Many attempts at trying, and I cannot get to the answer. I am doing something wrong. Just having the answer is not helping. I have tried using the product and quotient rule(s) but am probably not simplifying correctly. If someone can show the steps that would really be great.

Thanks

Regards

Craig.

Tricky (for me anyway) Differentiation

Here are some steps.

Here is the start.

Then

But something is wrong. I need to get to:

I cannot see how simplifying will get the terms I need to cancel.

Cannot seem to get there. I have pages of working, and I am doing something stupid.