On May 25, 12:50 pm, William Elliot <ma...@panix.com> wrote: > On Fri, 24 May 2013, baclesb...@gmail.com wrote: > > On Friday, May 24, 2013 3:28:09 AM UTC-4, William Elliot wrote: > > > > > Suppose f:[0, oo) --> R is increasing, differentiable and has a > > > > > finite limit as x --> oo. Then, must we have lim x --> oo f'(x) = > > > > > 0? I guess not, but couldn't find a counter example. > > How about this: with the same lay out as before: f(n+1)-f(n)=f'(cn). > > Give it up, counter examples have been presented.