# Symbols:Greek/Delta/Arbitrarily Small Change

## Arbitrarily Small Change

$\delta x$

$\delta x$ is often used to mean an arbiitrary small change or difference in the value of the (real) variable $x$.

For example, for the definition of derivative:

$\displaystyle \dfrac {\d y} {\d x} = \lim_{\delta x \mathop \to 0} \dfrac {\delta y} {\delta x} = \lim_{x_2 - x_1 \mathop \to 0} \dfrac {y_2 - y_1} {x_2 - x_1} = \lim_{\text{change in } x \mathop \to 0} \dfrac {\text{change in } y} {\text{change in } x}$

The $\LaTeX$ code for $\delta x$ is \delta x .