What Are Functions?

The concept of a function is one of the most important, fruitful, and indispensible tools in mathematics. The term function appeared for the first time in Gottfried Leibniz’s mathematics manuscripts of 1673. The further development of the concept of a function is connected with Leonhard Euler’s name, who was one of the greatest mathematicians of all time. Euler’s work broadened the concept of a function and made it a core part of modern mathematics.


A function is a correspondence or rule that assigns to every element in a set D exactly one element in a set R. The set D is called the domain of the function, and ...

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