Question

How do you find the 10th term in the geometric sequence -2,6,-18,...?

Answer 1

`39366`

Explanation:

Formula for `a_n`th term geometric series: `ar^(n-1)`, where `a` is the first term and `r` is the common ratio.

In the sequence `[-2, 6, -18, ...]`
`a = -2` and `r = (a_2)/(a_1) = 6/(-2) = -3`
`therefore a_10 = ar^(10-1) = -2 * -3^9 = 39366`