The question below has been taken from the C2 June 2015 Exam paper, this is question 9c and on Binomial expansion and Logarithms.
A few of you have mentioned that you have struggled with this question so I thought i'd explain how to go through and answer the question. The red marks note the annotation of how I went about doing it and why and the black pen shows my working out. I hope you find this useful to understand where you may have gone wrong or helped you to understand the question a little clearer.
Please feel free to get in touch should you wish me to do any more of these types of questions, I'm always happy to help.