Question

HELP!!

How many terms are in the arithmetic sequence 5, 1, −3, …, −99?

Answer 1

the common difference = 1 -5 = -4

nth term = 5 +(n-1)*-4
last term = -99 :-
-99 = 5 -4n + 4
-99 = 9 - 4n
4n = 108
n = 27

there are 27 terms in this series

Answer 2

There are 26 terms in this arithmetic sequence. They are all subtracted by 4.