Question

How do I find three arithmetic means between -2 and 12?

Answer 1

a1 a2 a3 a4 a5
-2 12

the 3 terms in the middle are the means.

arithmetic mean would have us defined an arithmetic sequence of the format:

an = a1 + d(n-1)

Answer 2

as such

a5 = a1 + d(4)

a5-a1 = d(4)

a5-a1
----- = d ; would be the difference between terms
4

Answer 3

or, a3 would be the normal use of the term average, between -2 and 12

12-2 = 10/2 = 5

a1 a2 a3 a4 a5
-2 5 12

and a2 is the average of a1 and a3; similar concept for a4