Master Method
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Compared with the iteration method, the master method is much easier to use once you understand how to use it. The hardest part about the master method is understanding the language of the master theorem.
Let
       and
      and
       be constants, let
      be constants, let
       be a function, and let
      be a function, and let
       be defined on the nonnegative integers by the recurrence:
      be defined on the nonnegative integers by the recurrence:

where we interpret
       to mean either
      to mean either
       or
      or
       .  Then
      .  Then
       can be bounded asymptotically as follows:
      can be bounded asymptotically as follows:
      1.  If
       for some constant
      for some constant
       , then
	
      , then
       .
      .
      2.  If 
       , then
	, then 
       .
	.
      3.  If
       for some constant
	for some constant
       , and if
 
	, and if 
       for some constant
	for some constant
       and all sufficiently large
 
	and all sufficiently large 
       , then
	, then 
       .
	.
      
    
Basically all you have to do to solve a recurrence relation is figure out which of the three cases your recurrence falls into and apply the given formula to get the answer!
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