9514 1404 393
Answer:
d(4) = -24
Step-by-step explanation:
We assume your formula is intended to be ...
[tex]d(n)=3(-2)^{n-1}[/tex]
This describes a geometric sequence with a first term of 3 and a common ratio of -2. That is, each term is -2 times the previous one. Then the first few terms of the sequence are ...
3, -6, 12, -24, 48, -96, ...
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In case you're interested in the 4th term, it is -24.
