Answer:
- 3, - 8, - 13
Explanation:
we know
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
here a₁ = 2 n = 5 and d has to be found , then
- 18 = 2 + (5 - 1)d
- 18 = 2 + 4d ( subtract 2 from both sides )
- 20 = 4d ( divide both sides by 4 )
- 5 = d , then
a₂ = 2 - 5 = - 3
a₃ = - 3 - 5 = - 8
a₄ = - 8 - 5 = 13
the three arithmetic means are - 3, - 8, - 13