Question

The first term of an arithmetic sequence is -2. The eighth term of the sequence is 26. What is the common difference of the arithmetic sequence?

Answer 1

d = 4

Explanation:

a₁ = -2

a₈ = aₙ = 26

n = 8

aₙ = a₁ + d(n-1)

d = aₙ - a₁ / (n-1)

d = 26 -(-2) / (8-1)

d = 26 + 2 / 7

d = 28 / 7

d = 4

-2

-2 + 4 = 2

2 + 4 = 6

6 + 4 = 10

10 + 4 = 14

14 + 4 = 18

18 + 4 = 22

22 + 4 = 26

Answer 2

d = 4

Explanation:

The n th term of an arithmetic sequence is

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Given a₁ = - 2 and a₈ = 26 , then

- 2 + 7d = 26 ( add 2 to both sides (

7d = 28 ( divide both sides by 7 )

d = 4