Question

Can some explain to be on what to do with a question like this:

Suppose a movie theater has 42 rows of seats and there are 29 seats in the first row. Each row after the first has 2 more seats than the row before it. How many seats are in the theater?

Answer 1

I know it's using gemoetric or arithmetic stuff

Answer 2

ok. so can u tell me how many seats in the second row?

Answer 3

31 right?

Answer 4

first row has 29 common difference is d=2, your a=29 , d=2
therefore in 42 rows
there are total of
\[Sn=\frac{ n }{ 2 }(2a+(n-1)d)=\frac{ 42 }{ 2 }(2*29+(42-1)2)\] you can calculate now

Answer 5

it should be 2940 seats

Answer 6

yea. 29 + 2
and in the third its 29 + 2 + 2 = 29+4
in the fourth, it is 29 + 6
and so on...
so the nth row would contain 29 + (n-1)*2

This is the general term of an A.P.

and you are asked to find the sum of the first 42 terms.

Answer 7

Dang that's alot of seats,and yeah I calculated that! Thank you..