Standard Form of a Line

The standard form of a linear equation is

Ax + By = C.

The advantage of standard form is that it accomodates both horizontal lines (A = 0) and vertical lines (B = 0).

The disadvantage is that A, B, and C do not stand for anything obvious (like the slope or y-intercept). In fact, they are not unique: if we double them all, we get back the same line! You can check this with the following example.

x + 2y = 3

2x + 4y = 6

These two equations, both in standard form, represent the same line.