Question

In an arithmetic sequence, if a2= 5 and a10= 19 find a6

Answer 1

Answer:

a₆ = 12

Step-by-step explanation:

The nth term of an arithmetic sequence is

$a_{n}$ = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Given a₂ = 5 and a₁₀ = 19 , then

a₁ + d = 5 → (1)

a₁ + 9d = 19 → (2)

Subtract (1) from (2) term by term to eliminate a₁

8d = 14 ( divide both sides by 8 )

d = 1.75

Substitute d = 1.75 into (1)

a₁ + 1.75 = 5 ( subtract 1.75 from both sides )

a₁ = 3.25

Then

a₆ = 3.25 + 5(1.75) = 3.25 + 8.75 = 12