find the arithmetic mean of a_n
a_(n-1) = 8 and a_(n+1)=- 3
To find the arithmetic mean of a_n, we can sum up a_(n-1) and a_(n+1) and then divide by 2.
a_(n-1) = 8
a_(n+1) = -3
Arithmetic mean = (8 + (-3)) / 2
Arithmetic mean = 5 / 2
Arithmetic mean = 2.5
Therefore, the arithmetic mean of a_n is 2.5.