Key Terms

horizontal line

A horizontal line is the graph of an equation that can be written in the form $y=b$. The line passes through the y-axis at $\left(0,b\right).$

intercepts of a line

Each of the points at which a line crosses the x-axis and the y-axis is called an intercept of the line.

linear equation

An equation of the form $Ax+By=C,$ where $A\text{and}B$ are not both zero, is called a linear equation in two variables.

ordered pair

An ordered pair $(x,y)$ gives the coordinates of a point in a rectangular coordinate system. The first number is the $x$-coordinate. The second number is the $y$-coordinate.

$$\underset{x\text{-coordinate},y\text{-coordinate}}{\left(x,y\right)}$$

11.1

origin

The point $\left(0,0\right)$ is called the origin. It is the point where the $x$-axis and $y$-axis intersect.

quadrants

The $x$-axis and $y$-axis divide a rectangular coordinate system into four areas, called quadrants.

slope of a line

The slope of a line is $m=\frac{\text{rise}}{\text{run}}$. The rise measures the vertical change and the run measures the horizontal change.

solution to a linear equation in two variables

An ordered pair $\left(x,y\right)$ is a solution to the linear equation $Ax+By=C$, if the equation is a true statement when the x- and y-values of the ordered pair are substituted into the equation.

vertical line

A vertical line is the graph of an equation that can be written in the form $x=a$. The line passes through the x-axis at $\left(a,0\right).$

x-axis

The x-axis is the horizontal axis in a rectangular coordinate system.

y-axis

The y-axis is the vertical axis on a rectangular coordinate system.