Question

What is the sum of the geometric sequence 4, 16, 64, ... if there are 8 terms? (6 points)

Answer 1

Answer:

87380

Step-by-step explanation:

The sum to n terms of a geometric sequence is

$S_{n}$ = $\frac{a(r^n-1)}{r-1}$

where a is the first term and r the common ratio

r = $\frac{16}{4}$ = 4 and a = 4, hence

$S_{8}$ = $\frac{4(4^8-1)}{4-1}$ = $\frac{4(65535)}{4}$ = 87380