SOLUTION: 23, 26, 30, 35....is the number of seats in a row of a theatre. 23 being the first row, 26 being the second and so on. give a general solution for the number of seats in the nth ro

Question 850063: 23, 26, 30, 35....is the number of seats in a row of a theatre. 23 being the first row, 26 being the second and so on. give a general solution for the number of seats in the nth row ?
Answer by swincher4391(1107) (Show Source): You can put this solution on YOUR website!
This is a quadratic arithmetic series (sometimes known as second difference)
We notice that the second difference is 1. (that is the difference is going up by 1).
In general if we have a second difference a, then the n^2 term is a/2.
We also know that the first term is 23, so find a_0 which is 21 (23-2).
so in the form an^2 + bn + c we have

We set this equal to one of our rows. We could use 1, but I will use a different one just to prove a point. We know that a_2 = 26. So plug in 2 and see if we get 26.

So our form is
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