Find the first term and the common difference. How do you use these to find the second term?
First Five: 10, 12, 14, 16, 18 Graph:
Practice makes perfect
We are told that the first row has 10 dominoes. Therefore, the first term in the sequence is a_1= 10. We are also told that each row has 2 more dominoes than the previous row. This means that the common difference is 2 and that each term in the arithmetic sequence can be found by adding 2 to the previous term.
rll
a_1 &&= 10
a_2=& 10+ 2&= 12
a_3=& 12+ 2&= 14
a_4=& 14+ 2&= 16
a_5=& 16+ 2&=18To graph the sequence we have to write the terms as ordered pairs, (n,a_n). Here, n is the position of the term and a_n is its value.
n
a_n
(n,a_n)
1
10
(1,10)
2
12
(2,12)
3
14
(3,14)
4
16
(4,16)
5
18
(5,18)
If we mark these points on a coordinate plane, we get the graph of the sequence.
