Question

The formula for any geometric sequence is a n = a 1 · r n - 1, where a n represents the value of the nth term, a 1 represents the value of the first term, r represents the common ratio, and n represents the term number. What is the formula for the sequence -3, -6, -12, -24, ...?

an = -3 · 2n - 1
an = -3 · (-2)n - 1
an = 2 · (-3)n - 1
an = -2 · (-3)n - 1

Answer 1

see explanation

Explanation:

The n th term of a geometric sequence is

`a_(n)` = a₁
`(r)^(n-1)`

where a₁ is the first term and r the common ratio

Here a₁ = - 3 and r = - 6 ÷ - 3 = 2, thus

`a_(n)` = - 3
`(2)^(n-1)`