Equation of Line in Standard Forms

5.3 Equation of Line in Standard Forms

An equation in $x$ and $y$ that is satisfied by the coordinates of every point on a line, and by no other point, is called the equation of the line.

Since every point on the X-axis has $y$-coordinate $0$ (and this is true only there), the equation of the X-axis is $y=0$. Likewise, since every point on the Y-axis has $x$-coordinate $0$, the equation of the Y-axis is $x=0$. …