# Linearity
**Linearity** is the property of a mathematical relationship (function) that can be graphically represented as a straight line. This initial, visual relationship needed to be formalized, so we came up with two properties that a linear relationship would always satisfy.
Given a map $f(x)$, $f$ is linear if it satisfies the two properties:
* **Additivity**: $f(x + y) = f(x) + f(y)$
* **Homogeneity of degree 1**: $f(ax) = a f(x) \;\; \forall \;\; a$
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Links to: [Linear Transformations](Linear%20Transformations.md) [Operators](Operators.md) [Does Linearity provide Information](Does%20Linearity%20provide%20Information.md)
References:
* https://en.wikipedia.org/wiki/Linearity