9514 1404 393
Answer:
an = 12(-1/2)^(n-1)
Step-by-step explanation:
Your sequence has a common ratio of ...
r = -6/12 = 3/-6 = -1/2
The first term is 12.
The explicit formula for the general term of a geometric sequence with first term a1 and common ratio r is ...
an = a1·r^(n-1)
Using the values for this sequence, the explicit formula you want is ...
an = 12·(-1/2)^(n -1)
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This could be rearranged to be ...
an = -24·(-2)^(-n)
