Exercise 42 Page 205

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. To graph the sequence we have to write the terms as ordered pairs, $\left(n,a_n\right).$ 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.