from x=6 and x=9

I need to find the arc length of this equation:

What I know: The equation for arc length is [integral of sqrt(1 + (f'(x))^2)]

What I'm stuck on: When I plug the equation into the arc length equation, I get lost. The hard part for me is after I find the number under the square root, then I have NO IDEA on how to do the integral under the square root!

Help please, thanks