\(\frac{n(n - 1)}{2}\)
\(\frac{n(n + 1)}{2}\)
\(\frac{(n + 1)(n + 2)}{2}\)
n(2n + 1)
Correct answer is C
\(\frac{(n + 1)(n + 2)}{2}\)
If n = 1, the expression becomes 3
n = 2, the expression becomes 6
n = 4, the expression becomes 15
n = 5, the expression becomes 21