Question

Determine whether the sequence is arithmetic or geometric.

Sequence 1: –10, 20, – 40, 80, ...
Sequence 2: 15, – 5, – 25, – 45, ...
Which of the following statements are true regarding Sequence 1 and Sequence 2.

Both sequences are arithmetic.
Sequence 1 is arithmetic and Sequence 2 is geometric.
Both sequences are geometric.
Sequence 2 is arithmetic and Sequence 1 is geometric.

Answer 1

What is the difference between arithmetic and geometric?

Answer 2

Arithmetic has a constant difference between terms and geometric has a constant ratio between terms @zimmah

Answer 3

Which sequence has a constant difference between terms?

Answer 4

I think it would be pretty hard to prove which one of them has a constant difference and which one doesnt. Given the options you have for an answer, that's pretty much all you need to do.

Answer 5

Sequence 1 @radar

Answer 6

Pretty hard = pretty easy, lol. I was merging two sentences in a wrong way.

It's not very hard or it's pretty easy, not pretty hard :p

Answer 7

-10 -x = 20

Can you solve x here?

Answer 8

Lets see -10 - 20 = -30
-20 -40 = - 60
-40 - 80 =-120 does that difference look constant?

Answer 9

yeah it's going up by 20 @radar

Answer 10

-30 to for the first pair difference
-60 for the second pair differenc
-120 for the next pair difference

That does not look like a constant 20 to me......??

Answer 11

You still think the first sequence is arithmetic sequence. Look at the evidence

Answer 12

30

Answer 13

What you must look at and answer this question, is the difference between each pair is the same.

Answer 14

is 20, 30, and 60 the same ??

Answer 15

If they are not the same, then it is not an arithmetic sequence.

Answer 16

Does 20 = 30?
does 30 = 60?
Don't think so. So they must be different. The difference is not constant.