Question

What is the 16th term of the following geometric sequence? 5, -10, 20, -40, 80, ...

Answer 1

The pattern in this sequence is *-2

so

80 is the 5th number

-160, 320, -640, 1280, -2560, 5120, -10240, 2048, -40960, 81920, -163840

The 16th number of this sequence is -163,840