Homework Help Forum: math- Algebra 2

Posted by Anonymous on Sunday, November 1, 2009 at 12:19pm.

An auditorium has 49 rows of seats. The first row contains 40 seats. As you move to the rear of the auditorium, each row has 3 more seats than the previous row. * I am pretty sure it involves both arithmetic series and explicit formulas but im not sure exactly how to go about it

• math- Algebra 2 - jim, Sunday, November 1, 2009 at 12:37pm

  OK. First, what exactly is the question? How many seats in the last row? How many seats in the auditorium? Let's figure a model to start. Row 1: 40 Row 2: 43 Row 3: 46 Row 4: 49 and so on. We want a formula that, given the row, will tell us how many seats. Multiplying the row by 3 has to be part of the answer, since there are 3 extra in each row, but that doesn't account for the initial row. We _could_ subtract 3 from the 40, imagining a row 0 with 37 seats that doesn't exist. Then our formula would be nice and neat: Seats in row = 37 + row * 3 Or we could equally well start at 40 but subtract 1 from the number of rows, to get: Seats in row = 40 + (row - 1) * 3 I'll use the first. s = 3r + 37 So in row 49 we have 3*49 + 37 seats.

  
  

• math- Algebra 2 - Kaps, Sunday, November 1, 2009 at 12:37pm

  you have 49 rows. row 1 has 40 seats. all u do is 40(n). 49*3=147 + 40= 187

  
  

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