For a positive integer

MATHEMATICS · Single correct · ISC · Mathematics · Algebra · Algebra

Problem

n

, the sum

\displaystyle\sum_{k=1}^{n}k(k+1)

is equal to (a)

\displaystyle\frac{n(n+1)(2n+1)}{6}

(b)

\displaystyle\frac{n^{2}(n+1)}{3}

(c)

\displaystyle\frac{n(n+1)(n+2)}{3}

(d)

\displaystyle\frac{n(n+1)(3n+1)}{6}