Arc Length Problem?

Here's the Problem:

Find the arc length of y = [(x^3)/6] + [1/(2x)] on [0.5,2]

I struggling with the algebra on this problem, can anyone be kind enough to help?

Note: I cannot use any form of integration techniques other than U-Subsitution or just taking the antiderivative. Cannot use trig sub, integration by parts, or partial fractions decomposition. These are in the next chapter. Thank You