13.1......... I believe this is the correct answer
Answer:
Step-by-step explanation:
a = 5
r = -5
n = 9
t_9 = a r^(n - 1)
t_9 = (-1)^n*5 (-5) ^ 8
t_9 = (-1)^9 * 5 * (-5) ^8
t_9 = -1 ( 1953125)
t_9 = - 1953125
The sequence seems to be that you add 1 and then multiply by 2, and then add 1 and multiply by 3, so I would assume you do 9 + 1 = 10, and then multiply by 4 to get 40 as your next number. I hope this helps!
