Question

Find the arithmetic mean, a n of the given terms.

Answer 1

We want to calculate a_n, that will be the arithmetic mean between a_(n-1) and a_(n+1).

We can calculate it as:

`\begin{gathered} a_n=(a_(n-1)+a_(n+1))/(2) \\ a_n=(4+(-9))/(2) \\ a_n=(-5)/(2) \\ a_n=-2.5 \end{gathered}`

Answer: a_n = -2.5