Definition:Difference Quotient

Definition
Let $V$ be a vector space over the real numbers $\R$.

Let $f: \R \to V$ be a function.

A difference quotient is an expression of the form:
 * $\dfrac {\map f {x + h} - \map f x} h$

where $h \ne 0$ is a real number.

Geometric Interpretation
The difference quotient is the slope of the secant line of the graph of $f$ connecting points $P_1 = \tuple {x, \map f x}$ and $P_2 = \tuple {x + h, \map f {x + h} }$.

Also see

 * Definition:Finite Difference Operator
 * Definition:Derivative