Question

Write the explicit formula for the geometric sequence. -5, 20, 80

Answer 1

Did you mean - 80? That's not a geometric sequence unless the 80 is negative.

Answer 2

yes

Answer 3

can you help me?

Answer 4

I have an answer, but I'm \not sure how \to explain how I got it.LOL

Answer 5

\[a _{n}=-5\times(-4)^{(n-1)}\]

Answer 6

Plug in n=1 and you get -5, plug in n=2 and you get 20, plug in ....etc

Answer 7

i understand now how to do it now thanks