Question

Please help me on 5 I don’t know what I did wrong on the last two

Answer 1

ANSWER:

$\begin{gathered} a_n=18-3(n-1) \\ a_{100}=-279 \end{gathered}$

STEP-BY-STEP EXPLANATION:

We have the following sequence:

$18,15,12,9\ldots$

Therefore, the sequence is:

$a_n=18-3(n-1)$

Now, when n is 100:

$\begin{gathered} a_{100}=18-3(100-1) \\ a_{100}=18-297 \\ a_{100}=-279 \end{gathered}$