Question

Find S10 and explain why it is impossible to find so for the series

2, 6, 18, ...

Find the number of terms in the series + 8 -12 +18 -
-307.546875

ANSWER BOTH WITH WORK SHOWN. USE FORMULAS

sn = n/2(t1 + (n-1)d)
OR
sn t1(1-r^n)/ 1-r

Answer 1

1. nth term is 8 but it may continue to decrease depending on the 4th number. Therefore it is impossible to find the nth expression.

2, 2(n+9)

Explanation:

2, 18 -20+38 -40.5+75.5 -81.12535+151.2517 -151.535 +303.754 -307.54...

nth term is n/2(t1-1)