Sample Response: No, the triangular numbers are not a direct variation. There is not a constant of variation between a number and its position in the sequence. The ratios of the numbers to their positions are not equal. Also, the points (1, 1), (2, 3), (3, 6), and so on, do not lie on a line.

What did you include in your response? Check all that apply.

The sequence is not a direct variation.
There is no constant of variation.
The sequence cannot be described by the equation
y = kx.
The points do not lie on a line.