# Graphing Points on a Coordinate Plane

### Linear Equations and Graphing

In this video, step-by-step instructions on how to graph points on a coordinate plane are presented.

## Graphing Points on a Coordinate Plane

#### Graphing on the coordinate plane is a way to visualize relationships between two quantities.

The diagram below shows the different parts of the coordinate plane.

The point where the x-axis and y-axis intersect is called the origin.
Notice that x-values to the right of the y-axis are positive and x-values to the left of the y-axis are negative. Similarly, y-values above the x-axis are positive and y-values below the x-axis are negative

#### An ordered pair of numbers is used to locate any point on the plane.

An ordered pair is enclosed in a pair of parentheses with the first number representing a location on the x-axis, the x-coordinate, and the second number representing a location on the y-axis, the y-coordinate. To locate a point on the coordinate plane, do the following:

3.  The second number is the y-coordinate.

 1. Start at the origin. 2. The first number is the x-coordinate. If it is positive, move to the right the appropriate number of units. If it is negative, move to the left the appropriate number of units. If it is positive, move up the appropriate number of units. If it is negative, move down the appropriate number of units.

Look at the coordinate grid below.The ordered pair for point A is $(3, -2)$. To locate point A, we move three units to the right and two units down. Also shown on the coordinate plane are points B, C, D, and E.

 $$\begin{array}{|ccc|} \hline \text{point} & (x,y) & \text{Quadrant}\\ \hline \hline A & (3,-2) & IV \\ \hline B & (-8, 5) & II \\ \hline C & (-3, -6) & III\\ \hline D & (0, 5) & \text{on y-axis}\\ \hline E & (-3\frac{1}{2}, 0) & \text{on x-axis}\\ \hline \end{array}$$

#### A little history:

When you graph points on a coordinate plain (also called a Cartesian coordinate system), you are using the work of René Descartes. Descartes (1596 – 1650) was a French mathematician, scientist and philosopher. His work provided the first systematic link between geometry and algebra.