Question

If a1 = 8 and an
An-1 + 2 then find the value of a4.

Answer 1

9514 1404 393

Answer:

a4 = 14

Explanation:

Use the recursive definition repeatedly.

a1 = 8

a2 = a1 +2 = 8 +2 = 10

a3 = 10 +2 = 12

a4 = 12 +2 = 14

_____

The recursive definition tells you the terms of the sequence have a common difference of 2. The explicit formula for a term of the sequence can be written as ...

an = 8 + 2(n-1)

Then a4 is ...

a4 = 8 +2(4 -1) = 8+6

a4 = 14