Linear equations in two variables and functions

Linear equations in two variables

A linear equation in two variables, such as $Ax+By=C$, has a straight line for its graph.

Standard form of a linear equation of two variables is

$Ax+By=C$

where $x$ and $y$ are the variables, and $A$, $B$, and $C$ are real numbers.

The $x$ and $y$ values that make the equation a true statement are the solution of the equation. The solution is written as an ordered pair, $(x,y)$ — that is, the $x$ value first, then the $y$ value.

Sections in this chapter

Slope of a line

Computing the slope of a line, and parallel and perpendicular lines.

Equations of a line

Standard, slope-intercept, and point-slope forms of a line.

Relations and functions

Relations and ordered pairs, functions and the vertical line test, function notation, evaluating functions, reading values from a graph, and domain and range.

Graph of functions

Linear and constant functions.