It is customary that we do not leave radicals in denominators.
We multiple the fraction by a form of one to remove the radical from the denominator.
Remember multiplying a number by one or a form of one does not change the number's value.
Here is an example of rationalization: 
=    =    =   =   =   = 

If we were to change    to exponential form (5/41/3)

(5/41/3)(42/3/42/3) =

5(42/3)/41/3 + 2/3 =

5(161/3)/43/3 = 

5(81/321/3)/4 =

10(21/3)/4 = 

5(21/3)/2  =

There is another form of problem that require rationalization. This is a problem such as     This is solve by multiplying the fraction by the denominator's conjugate       in the form of one. That is