Triangular numbers can be represented with equilateral triangles formed by dots. The first five triangular numbers are 1, 3, 6, 10, and 15. Is there a direct variation between a triangular number and its position in the sequence? Explain your reasoning.

_____________________

1 answer

Yes, there is a direct variation between a triangular number and its position in the sequence.

The nth triangular number can be calculated using the formula Tn = n(n+1) / 2, where n represents the position in the sequence.

For example, the 4th triangular number can be calculated by plugging in n=4 into the formula: T4 = 4(4+1) / 2 = 10.

As seen in the above example, the triangular number increases as the position in the sequence increases by a constant rate according to the formula. Therefore, there is a direct variation between a triangular number and its position in the sequence.