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,

General formula for geometric sequence is:

Putting the values of a1 and r

Hence,
The correct answer is:
b.) f(n) = 3 • (-2)^(n-1)
Keywords: Geometric Sequence, Explicit formula
Learn more about geometric sequence at:
#LearnwithBrainly
Answer:
Step-by-step explanation:
A quadratic equation can be factorised if and only if there are rational roots.
For any quadratic equation the discriminant decides about the nature of roots.
Thus only if the discriminant is a perfect square we can have rational roots and in this case only factorization is possible.
In the given equation

Since 1 is a perfect square we can factor and solve

The answer is B because the x doesn’t repeat in that one.