alternate -> alternative.

Doc/library/decimal.rst

@@ -984,7 +984,7 @@ method.  For example, ``C.exp(x)`` is equivalent to
 
 The usual approach to working with decimals is to create :class:`Decimal`
 instances and then apply arithmetic operations which take place within the
-current context for the active thread.  An alternate approach is to use context
+current context for the active thread.  An alternative approach is to use context
 methods for calculating within a specific context.  The methods are similar to
 those for the :class:`Decimal` class and are only briefly recounted here.
 

Doc/tutorial/inputoutput.rst

@@ -250,7 +250,7 @@ having to load the entire file in memory.  Only complete lines will be returned.
    >>> f.readlines()
    ['This is the first line of the file.\n', 'Second line of the file\n']
 
-An alternate approach to reading lines is to loop over the file object. This is
+An alternative approach to reading lines is to loop over the file object. This is
 memory efficient, fast, and leads to simpler code::
 
    >>> for line in f: