Question

Write the explicit formula for the geometric sequence. Then find the fifth term in the sequence.

Answer 1

Answer: 1; A

2;C

3;B

4;A

5;B

Step-by-step explanation:

Answer 2

Sequence: -4, 8, -16

rate of increase: -16/8 = -2
 
If you make A1 the first term in the sequence you must use (n-1) in the explicit formula. If you go backwards in the sequence to find A0 = 2 then you would use n.

The don't have A0 = 2 listed as an option so we use A1 = -4 and (n-1) terms.

An = -4(-2)^(n-1)

Solving for the 5th term A5, use n = 5

A5 = -4(-2)^(5-1)
A5 = -4(16)
A5 = -64

So the answer is B.