Constant functions

Definition: A function of the form
$$\begin{align} y(x) & = c, \end{align}$$

where $c$ is a number, is called a constant function.

Remark 1: The graph of a constant function is a horizontal line.

Remark 2: The function $y(x)=c$ has a zero for every $x$ if $c=0$ and no zeros if $c\neq 0$.

Example: The function $y(x)=4$ is an example of a constant function.