The total seating capacity of an auditorium is 1,065. The first row has 21 seats arithmetic series and each row has one seat more than the row in front of it. How many rows of seats are there in the auditorium?

Answer 1

In your arithmetic series:
a = 21
d = 1
n = ??
sum(n) = 1065

1065 = (n/2)(2(21) + (n-1)(1) )
2130 = n(42 + n - 1)
2130 = n^2 + 41n
n^2 + 41n - 2130 = 0
(n-30)(n + 71) = 0

n = 30 or n = -71 , but n > 0

there are 30 rows

Answer 2

Bubu kayu

Answer 3

What formula did you use? What is it called?

Answer 4

Way pulos

Answer 5

I learned na bogo jud kog math