Introduction: In the context of measuring changes, the notion of marginality is used in economics to indicate the derivative.
Definition: In economics the derivative $y'(x)$ of a function $y(x)$ is called the marginal change of the function $y(x)$.
Example: Let $C(x)=5x^3-10x+12$ be a cost function. Then the marginal cost function is given by $MC(x)=C'(x)=15x^2-10$.
Definition: In economics the derivative $y'(x)$ of a function $y(x)$ is called the marginal change of the function $y(x)$.
Example: Let $C(x)=5x^3-10x+12$ be a cost function. Then the marginal cost function is given by $MC(x)=C'(x)=15x^2-10$.