You can put this solution on YOUR website! I was looking at this problem last night, and I had answered it for you, but due to a computer glitch, I lost my internet connection and I could not post it for you. Now, I think the answer posted by the other tutor is incorrect. This is the way it should be solved.
The first step is to recognize and sort out any factors of this expression that are perfect squares. In this case 4 and a^2 are perfect squares, which would leave 3 and b as what I call the "leftover" factors. Sort it out like this:
Take the square root of the first part, and leave the second part in the radical sign:
For additional explanation on radicals please go to my website by clicking on my tutor name "rapaljer" anywhere in algebra.com. Take the first link on my home page which is "Basic and Intermediate Algebra" and look in the Basic Algebra for Chapter 5 on Square Roots. Sections 5.01 and 5.02 will give a much more detailed explanation with examples, exercises, and ALL the answers. See also my pages called MATH IN LIVING COLOR, where many of these exercises are solved in color.