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## Tinascott Group Title Write the explicit formula for the geometric sequence. -5, 20, 80 one year ago one year ago

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1. BangkokGarrett

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

2. Tinascott

yes

3. Tinascott

can you help me?

4. BangkokGarrett

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

5. BangkokGarrett

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

6. BangkokGarrett

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

7. Tinascott

i understand now how to do it now thanks