On = 38 - 9n
Explanation:
Note the common difference d between
consecutive terms
d= 20 - 29 = 11 - 20 = - 9
This indicates the sequence is arithmetic with n
th term
On
= apt (n - 1)d
where a, is the first term and d the common
difference
Here a, = 29 and d=- 9, thus
An = 29 - 9 (n - 1) = 29 - 9n + 9 = 38 - 9n