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 Question from Alynna, a student: You are given the following pattern: 9,-4,6,-8,3,... Create a formula for the nth figure. I have trouble finding the formula, I need help trying to find it.

Hi Alynna,

I see this as two interwoven sequences, the first being 9, 6, 3, ... Do you see what kind of sequence this is? The second is -4, -8, ... Do you see what kind of sequence this is?

Your formula for the $n^{th}$ term $a_n$ is going to say: if $n$ is odd then $a_n = ...$ and if $n$ is even then $a_n = ...$

I hope this helps,
Penny

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