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Horizontal and Vertical Lines

Equations of horizontal and vertical lines only have onevariable. The equation $x=4$represents a vertical line whichcrosses the$x$-axisat the point$\left(4,0\right)$. Everyordered pairwith$4$as its first coordinate is asolution. (The equation means “$x$is equal to$4$, and$y$can be whatever it wants.”)

Similarly, the equation

$y=-3$

is a horizontal line whichcrosses the$y$-axisat$\left(0,-3\right)$.

The point where the horizontal and vertical lines intersect is also easy to find.