## BrittanyFrench Group Title 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? one year ago one year ago

1. BrittanyFrench Group Title

I know it's using gemoetric or arithmetic stuff

2. Saikam Group Title

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

3. BrittanyFrench Group Title

31 right?

4. itsmylife Group Title

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

5. itsmylife Group Title

it should be 2940 seats

6. Saikam Group Title

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.

7. BrittanyFrench Group Title

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