Multiplication and Division of Radicals
Key Questions

#sqrt(a/b)= [sqrta]/[sqrtb]# #sqrta xx sqrtb=sqrt(axxb)# or
#sqrtasqrtb=sqrt(axxb)# 
When you have a root (square root for example) in the denominator of a fraction you can "remove" it multiplying and dividing the fraction for the same quantity. The idea is to avoid an irrational number in the denominator.
Consider:
#3/sqrt2#
you can remove the square root multiplying and dividing by#sqrt2# ;
#3/sqrt2*sqrt2/sqrt2#
This operation does not change the value of your fraction because#sqrt2/sqrt2=1# anyway and your fraction does not change by multiplying#1# to it.Now you can multiply in the numerator and denominator:
#3/sqrt2*sqrt2/sqrt2=(3*sqrt2)/((sqrt2)*(sqrt2))# giving:
#(3*sqrt2)/2# you have removed the square root from the denominator! (ok it went to the nominator but this is ok).Now a problem for you; what happens when the root is not alone???!!!
If you have:
#3/(1+sqrt2)# ???
You can use the same technique but...what do you use to multiply and divide?
HINT: look at what happens if you do this:
#(1+sqrt2)*(1sqrt2)# 
Multiplication
#sqrt{a}cdot sqrt{b}=sqrt{a cdot b}# Division
#{sqrt{a}}/{sqrt{b}}=sqrt{a/b}#
I hope that this was helpful.