Given:
Find-: Rate of change or check linear function.
Sol:
Rate of change is:
[tex]=\frac{y_2-y_1}{x_2-x_1}[/tex]
Where,
[tex]\begin{gathered} (x_1,y_1)=\text{ First point} \\ \\ (x_2,y_2)=\text{ Second point} \end{gathered}[/tex]
So the rate of change.
[tex]\begin{gathered} =\frac{15-0}{7-2} \\ \\ =\frac{15}{5} \\ \\ =3 \end{gathered}[/tex]
The second point is:
[tex]\begin{gathered} =\frac{18-15}{9-7} \\ \\ =\frac{3}{2} \end{gathered}[/tex]
So rate change is different from the other point so it is not a linear function.