Definition: A function of the form
\[
y(x)=ax+b,
\]
where $a$ and $b$ are numbers ($a\neq 0$), is called a linear function.
Remark 1: For $a=0$ this is a constant function.
Remark 2: The graph of a linear function is a straight line.
Example: De function $N(t)=2t+3$ is an example of a linear function.
\[
y(x)=ax+b,
\]
where $a$ and $b$ are numbers ($a\neq 0$), is called a linear function.
Remark 1: For $a=0$ this is a constant function.
Remark 2: The graph of a linear function is a straight line.
Example: De function $N(t)=2t+3$ is an example of a linear function.