Question

Write an equation for the nth term of the given arithmetic sequence.
-13, -28, -43, -59,

Answer 1

Oops, it's not an arithmetic squence. Please prove it.

Answer 2

Agreed, I don't see the sequence

Answer 3

well thats all the question told me but the answers they gave me are

a) a^n = -15n - 28
b) a^n = -13n + 1
c) a^n = -15n + 2
d)a^n = 15n - 28

Answer 4

Just use brute force. Start plugging n's in each choice and see which one results in a matching sequence

Answer 5

Don't try to solve it. The answer is "None of the Above". It is NOT an arithmetic sequence.

Answer 6

Ok thanks!

Answer 7

Do you know why this is so?

Answer 8

Actually, the brute force method is incorrect also

Answer 9

-13, -28, -43, -59,

-28 - (-13) = -15 <== This could be the common difference.
-43 - (-28) = -15 <== Okay, I almost believe it.
-59 - (-43) = -16 <== That's no good. We do NOT have a common difference. If it has said -58, we would be in business.

Answer 10

Exactly, what I was about to ask. Should that be 58?

Answer 11

-58 I meant

Answer 12

It might be! they might have had a typo or something. ill try it with -58 and see if i get an answer

Answer 13

If it were me on an exam, I would first state that it is not an arithmetic sequence - and prove it. I would then change the last value to -58 and work the problem as if it were so intended.