Question

What is the value of the 11th term in the sequence -3, -6, -12, -24, ...?

A. -6,144
B. -118,098
C. -3,072
D. -354,294

Answer 1

C

Explanation:

There is a common ratio r between consecutive terms in the sequence, that is

- 6 ÷ - 3 = - 12 ÷ - 6 = - 24 ÷ - 12 = 2

This indicates the sequence is geometric with n th term

`a_(n)` = a₁
`r^(n-1)`

where a₁ is the first term and r the common ratio

Here a₁ = - 3 and r = 2 , thus

a₁₁ = - 3 ×
`2^(10)` = - 3 × 1024 = - 3072 → C