Congrats if you did. I was searching around to refresh myself and found some links, this one "might" help, maybe look at the bottom of page 1 here:
http://www.public.iastate.edu/~aaall...5-B2HW3Sol.pdf
PS: And you might be famous by now. In case you haven't received tons of calls and requests for your autograph yet, when I googled "maximum curvature of ln (x)" your post here in this thread on TFP was the fourth find at google.