# How do you identify the 8th term of the geometric sequence -2, -12, -72 ...?

##### 1 Answer
Jun 23, 2018

${a}_{8} = - 559872$

#### Explanation:

$\text{the n th term of a geometric sequence is}$

•color(white)(x)a_n=ar^(n-1)

$\text{where a is the first term and r the common ratio}$

$\text{here "a=-2" and } r = \frac{- 12}{- 2} = \frac{- 72}{- 12} = 6$

${a}_{8} = - 2 \times {6}^{7} = - 559872$