Rate of Change

Rate of Change is used to describe the ratio of a change in one variable compare to a change of another variable

If there is a function ${\displaystyle f(x)=y}$ then the rate of change of the function ${\displaystyle f(x)}$ correspond to the rate of change of variable z is

${\displaystyle {\frac {\Delta y}{\Delta x}}={\frac {\Delta f(x)}{\Delta x}}}$

Example

If there are two points ${\displaystyle (1,3)}$ and ${\displaystyle (2,7)}$

${\displaystyle {\frac {\Delta y}{\Delta x}}={\frac {\Delta f(x)}{\Delta x}}={\frac {7-3}{2-1}}=4}$