Pull out the highest power of 
from each radical expression, then divide through the numerator and denominator by the largest power of overall.
The largest power in the cube root is
; the largest power in the fourth root is 
:
Now the largest power in the numerator and denominator is
, so we get
Every term containing approaches 0 as 
, which leaves us with
The largest power in the cube root is
Now the largest power in the numerator and denominator is
Every term containing
