The first row of seating in section H of the Concert Area has 7 seats. In all, there are 25 rows of seats in section H, each row containing 2 seats more than the row preceding it. How many seats are in section H?
My attempt:
it is an arithmetic problem i guess.
a1=7
a1+(n-1)d
7+(25-1)2=55 seats
is this how you do this problem?
The first row has 7 seats, since k=0 zero when you are at the first row. If you move up to the second row k=1, so there are 7+2(1)=9 seats. If you move up to the third row k=2, so there are 7+2(2)=11 seats. You can continue this for k=3,...,24 (since there are 25 rows and we consider the first row to be row 0). The notation Plato posted tells you to add up each one of these terms. So,
, where is the index of the summation, 0 is the lower bound (the initial value of k) and 24 is the upper bound (the final value of k). Thus, you begin at k=0 and add the following terms up until you get to k=24.
Hopefully that clears things up.