Question 144947
Your problem:
sqrt(18x^2 y^3)

Start by "factoring" terms inside the radical.  For example, let's expand the x's and the y's:
sqrt(18xxyyy)
When you see a "pair" pull it out of the radial:
xy[sqrt(18y)]

Now, expanding the 18:
xy[sqrt(2*3*3*y)]
Pulling out the pair of 3:
3xy[sqrt(2y)]

Does that make sense?