Answer:
1) a1 = -5, a(n) = a(n-1) + 2
Step-by-step explanation:
The explicit formula for an arithmetic sequence can be written ...
an = a1 +d(n -1)
The corresponding recursive formula is ...
a(1) = a1, a(n) = a(n -1) +d
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Comparing the above explicit formula to the one you're given, you see that ...
a1 = -5, d = 2
Using these values in the recursive formula gives you ...
a(1) = -5, a(n) = a(n-1) +2
