Answer
(a) $1,3,2,-1,-3,-2,1,3,2,-1$
(b) See graph.
Work Step by Step
(a) Given $a_1=1, a_2=3$ and $a_n=a_{n-1}-a_{n-2}$, we have $a_3=3-1=2, a_4=2-3=-1, ...$, we can list the first ten terms as $1,3,2,-1,-3,-2,1,3,2,-1$
(b) See graph.
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