Question 6, first part http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Mathematics%20(9709)/9709_s12_qp_32.pdf

Question

mathmale · Answer

Would you please invest some time and effort into analyzing and solving this problem before asking for help on it.  For example, do an Internet search for "stationary point," find out from the search results how to identify stationary points, and then do as much as you can towards that goal.  Then ask questions.  Good luck.

anonymous · Answer

I did, I found two roots, there's one more root which I can't find

anonymous · Answer

I need help with that

mathmale · Answer

Would you please share the work you have already done?  I've looked up "stationary point" myself, but ask that you explain in your own words what a "stationary point" is.  

Can you obtain (with screen shot or cell phone camera) an image of your work up to now and share it (Attach File)?  Then we can move forward.

mathmale · Answer

Which two roots have you identified, and have you checked them via substitution, determining whether or not the derivative of the given function equals zero for either or both?