Question

Write an explicit formula for the nth term of this sequence:

6, 11, 16, 21, . . .

1. an=5n+11

2. an=5n+1

3. an=21-5n

4. an=6n+1

Answer 1

2)an = 5n + 1

Explanation:

This is an arithmetic series.

6 , 11 , 16, 21 ,.....

First term =
`a_(1)` = 6

Common difference = d = second term - first term

= 11 - 6 = 5

nth term =
`a_(1)+(n-1)*d`

= 6 + (n - 1) * 5

= 6 + n * 5 - 1*5

= 6 +5n - 5

= 6 - 5 + 5n

= 1 + 5n