For each recursively defined sequence, list the first five terms and identify the sequence as arithmetic, geometric, or neither.  

1. $a_1 = 17$, $a_{n+1} = −a_n$ 

   Hint (a):

   $a_1 = 17$, $a_2 = −17$

2. $a_1 = 32$, $a_{n+1} = −5 +\frac { 1 } { 2 }a_n$ 

   Hint (b):

   $a_1 = 32$, $a_2 = 11$

   More Help (b):

   Look at the first five terms and imagine what a graph of the sequence would look like. Is it a line or a curve?

   Answer (b):

   Since the previous number ($a_n$) is multiplied by a constant (one-half), the sequence is geometric.

3. $a_1 = 81$, $a_{n+1} = a_n$ 

   Hint (c):

   $a_1 = 81$, $a_2 = 81$