The idea is to get it in a form that has no square root in the
denominator.

To get it that way we make the number under the radical become a
perfect square.  The smallest perfect square we can make 2 into
by multiplying is 4. So to make the denominator become 
instead of  we multiply the whole fraction by the "unit"
fraction  [it's a "unit" fraction because it
equals 1.]

×

Multiplying tops and bottoms (bottoms under the radicals)



Then the square root of 4 is just 2 so the final answer is



and there is no square root in the denominator.

Edwin