Mathematics

Problem

Let

S_n

denote the sum of the first

n

terms of an arithmetic progression. The sum of the terms from the

p^{\text{th}}

term up to and including the

q^{\text{th}}

term (where

p<q

) is a)

S_q+S_{p-1}

S_{q-1}-S_{p-1}

S_q-S_{p-1}

S_q-S_p