All should be there, except taylor series, which is found here:
The Attempt at a Solution
For part a, I got:
since force is the negative derivative of potential.
I'm pretty sure the answer to part b will involve a taylor expansion, but I'm not sure if the f(x) I use will be the equation I found in part a, or the derivative of the equation I found in part a. Additionally, I'm not sure how, in the answer we're supposed to get that's listed in the problem, they got (n-1) and the n term in the second part out of the exponent.
Thanks for any help!