Im currently in the process of completing an assignment that requires me to find the arc length of a particular function. In this case the function is:

f(x) = (4.5/(1+25e^-x)) + 2.8

from x = -8 to 8

Here's the catch; as the course im doing has yet to introduce integration by parts or substitution to us, im not allowed to use them.

If anyone could solve this problem, or offer any help whatsoever, it would be much appreciated!