Answer the following questions related to the sum of a constant sequence.

MATHEMATICS · Multi-part · A Level · Mathematics · Sequences and series · Sequences and series

Problem

Answer the following questions related to the sum of a constant sequence. (i) Define a finite series and write the general sigma–notation form for the sum of the first nn terms of a sequence a1,a2,…,ana_1,a_2,\ldots ,a_n. (ii) Starting from first principles (writing out all the terms explicitly), explain why ∑k=1n1=n\displaystyle \sum_{k=1}^{n} 1 = n for every positive integer nn. (iii) Distinguish between the sums ∑k=1n1\displaystyle \sum_{k=1}^{n} 1 and ∑k=1nk\displaystyle \sum_{k=1}^{n} k with respect to the type of sequence involved and the respective closed-form expressions for their sums.

Related theory

Browse the problem library