CAPE Pure Mathematics Unit 2 · May/June 2018 · Paper 1 · Question Q23

Given that \sum_{k=1}^n k(k+1) = S_n, then, for m < n, \sum_{k=m+1}^n k(k+1) =

1. (A)S_n - S_{m+1}
2. (B)S_{m+1} - S_m
3. (C)S_n - S_m
4. (D)S_n - S_{n-1}