Question

What is the 20th term in the following sequence?

-2, -6, -18, -54, -162...

Answer 1

-2324522934

Explanation:

These are the terms of a geometric sequence with n th term

`a_(n)` = a
`(r)^(n-1)`

where a is the first term and r the common ratio

r =
`(-6)/(-2)` = 3 and a = - 2, hence

`a_(20)` = - 2 ×
`3^(19)` = - 2324522934