Question

Evaluate the geometric series. Please help me!!

Answer 1

Answer:

- 85

Step-by-step explanation:

The n th term of a geometric series is

$a_{n}$ = a$(r)^{n-1}$

where a is the first term and r the common ratio

1$(-2)^{n-1}$ ← is the n th term of a geometric series

with a = 1 and r = - 2

The sum to n terms of a geometric series is

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

    = $\frac{1((-2)^{8}-1 }{-2-1}$

    = $\frac{256-1}{-3}$

    = $\frac{255}{-3}$

    = - 85