Learn how to graph an Arithmetic Sequence and a Geometric Sequence in this video math tutorial by Mario's Math Tutoring. We go through an example of each ty...
To find a 30 we need the formula for the sequence and then substitute n = 30. The formula for an arithmetic sequence is We already know that is a 1 = 20, n = 30, and the common difference, d, is 4. So now we have So we now know that there are 136 seats on the 30 th row. We can use this back in our formula for the arithmetic series.