Question

I REALLY NEED HELP! HELP FAST PLEASE!!! 1.) Classify the sequence as arithmetic, geometric, or neither. If there is not enough information to classify the sequence, choose not enough information. (3,-1,1/3,-1/9)
2.) Write the first five terms of the geometric sequence with a1=-2 and common t=ratio r=-5/2
a.) (-2,-9/2,-7,-19/2)
b.) (-2,-5,-25/2,-125/4)
c.) (2,-5,25/2,-125/4)
d.) (-2,5,-25/2,125/4)

Answer 1

You can see a common ratio between the terms of the sequence.

Start with 3.
If you multiply that by -1/3, you get -1.
Multiply -1  by -1/3 again and you get 1/3.
Clearly, the common ratio is -1/3.
Thus, the sequence is geometric.

2) Start with -2, and continue to multiply it by -5/2.

1: -2
2: 5
3: -25/2
4: 125/4

Thus, the answer is d.