Answer
$a_1 = 2$, $a_n = -2(a_{n - 1})$
Work Step by Step
In a recursive formula, we need to give the initial condition, $a_1$, which is the first item in the sequence:
$a_1 = 2$
To find the recursive formula of the sequence, we must first find the pattern.
In this exercise, $a_n$ is found by multiplying the previous term, $a_{n - 1}$, by $-2$:
$a_n = -2(a_{n - 1})$