[tex]f(x)=mx+b\to y=mx+b[/tex]
We have two points:
[tex](-2,\ -6);\ (0,\ 0)[/tex]
The point slope form of the line:
[tex]y-y_1=m(x-x_1)\\\\m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
substitute
[tex]m=\dfrac{0-(-6)}{0-(-2)}=\dfrac{6}{2}=3\\\\y-0=3(x-0)\\\\y=3x[/tex]
Answer:
[tex]f(x)=3x[/tex]
