Given that n is the length of the bottom edge of the backward L-shaped figures below, what sequence is generated by the total number of dots in each figure? What is the
Find a rule for the sequence. How does the figure number relate to parts in the shape?
Look at the two legs. One way to see figure 3, for example, is a row of 3 and a column of 2 above it (note: you can't count the dot in the corner twice). How would you analyze figure 4 in the same way?
Now use the idea to analyze the