A linear function is one whose formula can be written in the form
Ax + By = C where A, B, C are real numbers and A, B are not both 0. (This is standard form, too.)
[tex]\frac{x+4}{2} = \frac{y-4}{3}[/tex]
"Cross multiply."
[tex]3(x+4) = 2(y-4) \\ 3x+12 = 2y-8[/tex]
Subtract 12.
[tex]3x=2y-20[/tex]
Subtract 2y.
[tex]3x-2y=-20[/tex]
This matches up with standard form with A = 3, B = -2, C = -20.
It's a linear function.
