Answer:
[tex]a_{97}[/tex] = - 1247
Step-by-step explanation:
I think you copied the problem incorrectly. The sequence as it stands is not arithmetic. Instead of the first term being -1, maybe it should be +1. Then we have a common difference of -13. So, that is what I will presume to be true.
The formula to use is
[tex]a_{n} = a_{1} + (n - 1)d[/tex]
d = -13
[tex]a_{97}[/tex] = 1 + (97 - 1)(-13)
= 1 + 96(-13)
= 1 - 1248
= - 1247
