What are functions ? From an introduction of the basic concepts of functions to more advanced functions met in economics, engineering and the sciences, these topics provide an excellent foundation for undergraduate study.

# The sum of an infinite series

The partial sums of an infinite series form a new sequence. The limit of this new sequence (if it exists) defines the sum of the series. Two specific examples of infinite series that sum to e and pi respectively are described. Video tutorial 18 mins.