# Math Insight

### Applet: A linear function of one variable

The linear function $f(x)=ax$ is illustrated by its graph, which is the green line. Since $f(0)=a \times 0 =0$, the graph always goes through the origin $(0,0)$. You can change $f$ by typing in a new value for $a$, or by dragging the blue point with your mouse. The parameter $a$ is the slope of the line, as illustrated by the shaded triangle.

Applet file: linear_function_one_variable.ggb