The correct answer is:
b.) f(n) = 3 • (-2)^(n-1)
Further explanation:
Given sequence is:
3, -6, 12, -24, ...
We have to find the common ratio first.
Common ratio is the ratio between two consecutive terms of a geometric sequence.
It is denoted by r.
So,
[tex]Here,\\a_1=3\\a_2=-6\\a_3=12\\a_4=-24\\r=\frac{a_2}{a_1}=\frac{-6}{3}=-2\\\frac{a_3}{a_2}=\frac{12}{-6}=-2[/tex]
General formula for geometric sequence is:
[tex]a_n=a_1r^{n-1}\\Here\\a_n\ is\ the\ nth\ term\\a_1\ is\ the\ first\ term\\and\\r\ is\ common\ ratio[/tex]
Putting the values of a1 and r
[tex]a_n=3.(-2)^{n-1}\\f(n)=3.(-2)^{n-1}[/tex]
Hence,
The correct answer is:
b.) f(n) = 3 • (-2)^(n-1)
Keywords: Geometric Sequence, Explicit formula
Learn more about geometric sequence at:
- brainly.com/question/2048256
- brainly.com/question/2115122
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