Question

Write the explicit formula for the geometric sequence.

a1 = -5 a2 = 20 a3 = -80
A. an = -5 • (-4)n

B. an = -5(-4)n-1

C. an = -4(-5)n-1

D. an = -5 • (4)n

Answer 1

what is a2/a1?

Answer 2

also, unless we know when "n" starts; there are 2 possible options

Answer 3

The numbers are below the letter

Answer 4

im aware of the shortcut for writing the subs ...

you need to determine the common ration of the geometric sequence; which can be defined as a2/a1

Answer 5

*ratio that is ....