Question

What is the value of the 11th term in the following geometric sequence?

-5, -10, -20, -40

Answer 1

Answer: - 5120

Explanation:

The first thing is to find the common ratio , since it is a geometric sequence.

common ratio ( r ) = second term / first term

r = -10/-5

r = 2

Using the formula for the nth term of a geometric sequence ;

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

The 11th term will thus be:

`t_(11)` = -5 X
`2^(10)`

= -5 x 1024

= -5120