Find the sum of the first five terms of the G.P 2,6, 18 ....
A
484
B
243
C
242
D
130
E
121
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
\(S_{n} = \frac{a(r^n - 1)}{r - 1}\)
a = 2; r = 6/2 = 3.
\(S_{5} = \frac{2(3^5 - 1)}{3 - 1}\)
= \(243 - 1 = 242\)
Source: Myschool Past Questions Archive (Record #22644)