Function
Definition
A relation from a set A (Domain) to a set B (Codomain) such that every element in A is associated with exactly one element in B. Written as f: A→B. Types include Linear, Quadratic, Polynomial, and Exponential functions.
Example
"f(x) = 2x + 3 is a linear function. If x = 5, f(5) = 2(5) + 3 = 13. Every input x gives exactly one output — confirming it is a valid function."