The numbers of seats in the first 12 rows of a high-school auditorium form an arithmetic sequence. The first row has 9 seats. The second row has 11 seats.
Write a recursive formula to represent the sequence.
Write an explicit formula to represent the sequence.
How many seats are in the 12th row?..
Recursive formula:
S(n) = S(n-1) + 2, where S(1) = 9
Explicit formula:
S(n) = 7 + 2(n-1)
To find the number of seats in the 12th row:
S(12) = 7 + 2(12-1) = 7 + 2(11) = 7 + 22 = 29
There are 29 seats in the 12th row.