Question

What is the sum of the first 8 terms of the geometric series:

3+6+12+24+

0765

382

286

440

Answer 1

765.

Explanation:

Sum of n terms = a1 (r^n - 1) / (r - 1) where a1 = the first term and r = the common ratio.

Here r = 6/3 = 2 and a1 = 3.

Sum of 8 terms = 3 * ( 2^8 - 1) / 2 -1)

= 3 * 255

= 765 (answer).