CPM Homework Help : CC1MN Problem 5-59

Study the pattern below. Sketch and label the fourth and fifth figures. Then predict how many dots will be in the $100^{\text{th}}$ figure. Write an expression you can use to determine the number of dots in any figure.

$\Large\begin{array}{c c c} \bullet & \bullet & \bullet \end{array}\\ \; \; \text{Figure 1}$

$\Large\begin{array}{c c c} \bullet & \bullet & \bullet\\ \bullet & \bullet & \bullet \end{array}\\ \; \, \text{Figure 2}$

$\Large\begin{array}{c c c} \bullet & \bullet & \bullet\\ \bullet & \bullet & \bullet\\ \bullet & \bullet & \bullet \end{array}\\ \; \, \text{Figure 3}$

Hint:

In this pattern, you begin with $3$ dots and add $3$ more with each figure.
Use this description to help you with this problem.