First, I'm going to separate factor the expression inside of the square root.
sqrt[ (2/18) * (x^5) ]
sqrt[ (1/9) * (x^5) ]
We can take the square root of 1/9 easily, because 1 and 9 are both perfect squares. The square root of 1/9 is 1/3.
Looking at the x^5, we can separate it into x^2 * x^2 * x^1. The square root of x^2 is x. So, we now also have an x^2 on the outside because there are two x^2s in our expanded form.
