Integration - Dr. Evil is my teacher

Right I won't bore you with a sob story but this is a regular grade 12 class and we've been posed with this problem:

Find the arc length of this function across 0 -> 5:

I learned the formula of s = Integral of

So I began using the Riemann sums until I get here, I'm not quite sure how to proceed.

http://img26.imageshack.us/img26/6931/formulaz.jpg

If need be I will show how I got up to there, it just takes forever to use LaTeX.

PS: That should be x->infinity

Thanks!