anne attended her graduation rights, the auditorium consists of 20 seats on the first row, 24 seats on the second row, 28 seats on the third row, and soon there are over 30 rows of seat.
1. what is the first term?
2. what is the common difference?
3. what is the number of term?
4. how many seats are there in the auditorium?
answer pleaseee
Share
Verified answer
Step-by-step explanation:
Let:
an = number of rows on the nth row
n = row number
d = common difference
Sn = total number of seats
1.
a1 = 20 (number of seats on the first row)
2.
d = a2 - a1 = 24 - 20 = 4
3.
n = 30 (total number of rows)
4.
Sn = (n/2)[2a1 + (n-1)d]
Sn = (30/2)[2(20) + (30-1)(4)]
Sn = 2340