Thank you, I'm looking into the points you raised.
I've attached a graph of the function V(x). The maximum value on it shows 14.993. Can a 2nd derivative test prove this do you think?http://files.engineering.com/getfile.aspx?folder=73dc5224-aa4f-48db-9d11-91124ef669b6&file=Engtips_1.mcd