Question

Find the next three terms of the sequence 5,-10,20,-40

Answer 1

80, -160, 320

Explanation:

5,-10,20,-40

It's a Geometric sequence with:

r = -10/5 = -2

-40 × -2 = 80

80 × -2 = -160

-160 × -2 = 320

Answer 2

200,-1000,5000

Explanation:

First we need to find the common ratio

Take the second term and divide by the first

-10/2 = -5

To find the 5th term take the 4th term and multiply by the common ratio

-40*-5 = 200

To find the 6th term take the 5th term and multiply by the common ratio

200 *-5 = -1000

To find the 7th term take the 6th term and multiply by the common ratio

-1000*-5 = 5000