Question

Find the sum of the geometric series given a1=−2, r=2, and n=8.

A. -510
B. -489
C. -478
D. 2

Answer 1

A. -510

Explanation:

We are given the variable values:

• a = -2
• r = 2
• n = 8

Geometric series formula:

`s = \frac{a( {r}^(n) * - 1) }{r - 1}`

Plugging in values we have:

`s = \frac{ - 2( {2}^(8) - 1) }{2 - 1}`

Simplifying the equation we are left with:

`( - 2(255))/(1) = - 510`