The cheerleaders are practicing a dance routine in which all 36 of them need to be in a triangular formation. there will be two more cheerleaders in each row than the previous row. how many rows will be in the formation

If you start with 1 cheerleader in row A, then you'll have 3 cheerleaders in row B (add on 2), and then 5 cheerleaders for row C (add on another 2), etc etc.

Note how: 1+3+5 = 4+5 = 9 which is a perfect square. Also note that 36 is a perfect square.

Rule: The sum of the first positive n odd numbers is going to be equal to n^2. In the example of adding the first three odd numbers (1,3,5), we have n^2 = 3^2 = 9 as the sum

So as you can see, we'll have n = 6 rows because n^2 = 6^2 = 36 and

1+3+5+7+9+11 = 36

which is the sum of the first six positive odd numbers. So we'll have 1 cheerleader in row A, 3 in row B, 5 in row C, 7 in row D, 9 in row E, 11 in row F to have 6 rows total.