NEKG33 Mathematical methods for economists

Chapter 12 : Day 12: Summation sign

By Lund University

Today we will admire the pretty summation sign ∑.

Sums and the summation sign

Here, we will look at the summation sign and the rules that you can use to simplify expressions using the summation sign. These rules are not new, they are the same rules that we have seen before, such as the distributive law. However, earlier, we only considered the sum of two elements. We extend this to sums of an arbitrary number of elements.

Summation sign

Summation rules

Problem: Evaluate sums

Problem: Calculate sum

Problem: True or false for sums

Problem: Sums involving the mean