Find the next three terms of the sequence 80, –160, 320, –640

For a geometric sequence

The nth term for this sequence is given by:

       .....[1]

where

is the first term

r is the common ratio

n is the number of terms.

Given the sequence:

80, -160, 320, -640

Common ratio(r) is -2

Since,

Substitute the values we have;

We have to find the next three term of the given sequence:

Using [1] we have

Substitute the given values we have;

Similarly,

Therefore, next three terms in the given sequence are: 1280, -2560, 5120