Section 8.2 Points, Lines and Their Graphs

Vocabulary Graph/Plot – an ordered pair or a point in a numbered plane Horizontal Axis – x-axis Vertical Axis – y-axis Cartesian Plane – graphing grid, coordinate plane Origin – (0,0) on the Cartesian Plane

Vocabulary Coordinates – the x- and y- in an ordered pair Abscissa – the x-coordinate Ordinate – the y-coordinate Graph of an equation – set of all points that are the graphs of the solutions of the equation Intercepts – those points where the graph of the equation crosses an AXIS – for a linear equation, there are at most two intercepts: the x-intercept (where the graph crosses the x-axis) and the y- intercept (where the graph crosses the y-axis)

Standard Form of a Linear Equation ax+by=c, where a, b, and c are INTEGER real numbers and a and b are both not zero. a (“leading coefficient”) should be POSITIVE. a, b, and c do not HAVE to be integers, but the equation is not in standard form if they are not.

Graphing Linear Equations One method is to find the x- and y- intercepts, plot those and connect the points with a line. This is called the intercept method of graphing. To find the x-intercept, set y=0 and solve for x. To find the y-intercept, set x=0 and solve for y.

Example 1: Intercept Method

Graphing Vertical Lines x y

Graphing Horizontal Lines x y x y