ASAP 15 POINTS
The formula for any geometric sequence is an = a1 ∙ rn - 1, where an represents the value of the nth term, a1 represents the value of the first term, r represents the common ratio, and n represents the term number. What is the formula for the geometric sequence 1, -2, 4, -8, ...?
an = -8 ∙ (-2) n - 1
an = 1 ∙ (-2) n - 1
an = 1 ∙ 2 n - 1
an = -2 ∙ 1 n - 1