EDGE Math 8

Linear Equations in x and y

Example 1

Graph the equation $4 x + 3 y = - 12$ on a coordinate plane.

Solution

Since the equation $4 x + 3 y = - 12$ is linear in two variables, its graph is a line. Since two points determine a line, it is sufficient to find any two ordered pairs $(x, y)$ that satisfy the given equation. Two such ordered pairs are easily obtained by solving for the x- and y-intercepts as shown in the following table:

x	0	−3
y	−4	0

Thus, $(0, - 4)$ and $(- 3, 0)$ are two points on the line. Connecting these points gives the graph of $4 x + 3 y = - 12,$ as shown in the figure below.