Question

Write a recursive formula for the sequence

Answer 1

Option B: a1= 15 ,
`a_n = 2a_(n-1)- 4`

Explanation:

Given sequence is 15, 26, 48, 92, 180..........

First term is a1, so a1= 15

To get second term 26, we multiply the first term with 2

So it becomes 15*2 = 30

Then we subtract 4 from 30. so 30-4=26

To get third term 48,

previous term 26 *2 - 4= 52-4=48

a_n is the first term and a_(n-1) is the previous term

To get recursive formula

multiply the previous term by 2 and then subtract 4

So recursive formula becomes

`a_n = 2a_(n-1)- 4`

Option B is correct