FUNCTIONS Tutorial sheet-{I}

Description
The concept of function like that of sets has evolved over a long period of time. It is believed that R.Descartes (1596-1650 A.D.) introduced the word 'function' in 1637 A.D. where he used it to mean some integral power xn of a variable x. An explicit definition of function was given by James Gregory (1638-1675 A.D.) in his vera circuliet Hyperbolate Quadraturia (1667 A.D.)
Leibnitz used the word 'function' to mean quantities that depend on a variable. He was the first to use phrase 'function of x'. The notations f(x) was introduced by Euler in 1734 A.D. Finally, Lejeunne Dirichlet (1805-1859 A.D.) gave the definition of function which is presently used.

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