Question

Describe the following sequence as arithmetic, geometric or neither.

2, 4, 6, 12, 14. . . .

I think it's arithmetic because it's +2, but then there's 6 to 12 and that's +6, but then it's back to +2 when it goes to 12 to 14.

Answer 1

its neither, because there isn't a common difference (which would make it arithmetic) or a common ratio (which would make it geometric)

Answer 2

Thanks! That's the first explanation on this site that makes sense.

Do you know which of the following is the general term for the sequence a, -a, a, -a, . . .?

a(-1)n+ 1
(-a)n
(-1)an+ 1

Answer 3

it is the first one, but the exponent didn't copy over.
a(-1)^(n+1)

Answer 4

Thank you!