Answer:
geometric sequence
Step-by-step explanation:
A list of 3 numbers is not a "formula". It is a "sequence."
The differences between the numbers are ...
12 -(-3) = 15
-48 -12 = -60
These are not constant, so the sequence is not arithmetic.
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The ratios between the numbers are ...
12/-3 = -4
-48/12 = -4
These are constant, so the sequence is geometric.
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The formula for the n-th term of a geometric sequence is ...
an = a1·r^(n-1)
We have first term a1 = -3 and common ratio r = -4. So, the formula for this sequence is ...
an = -3(-4)^(n-1)
