Question

HELP

Which of the following represents the general equation for the geometric sequence?


-1, -2, -4, ...


an = 1 · 2n - 1

an = -2n - 1

an = 2n - 1

an = 1 · 2n + 1

Answer 1

Answer:

aₙ = -2ⁿ⁻¹

Step-by-step explanation:

Your geometric series  is

-1,-2,-4, …

The first term (a₁) is -1, and each successive term is twice the one before it (the common ratio, r)

The formula for the nth term of a geometric series is

aₙ = a₁rⁿ⁻¹

The general formula for your series is then

aₙ = -2ⁿ⁻¹