# Numbers and The Coordinate Plane

In the number line shown below, you can see the numbers to the left of zero, as well as to the right of zero. Negative numbers are real numbers that are less than the value of zero. So all numbers to the left of zero are negative numbers and are represented by the sign (-) which is placed in front of the number.

## Coordinate Plane

The coordinate plane contains both a horizontal and a vertical axis where you can see number lines intersected at right angles. X-axis is the horizontal axis on the coordinate plane whereas the vertical axis on the coordinate plane is the y-axis. The place where the two axis intersect each other, is known as the origin. The coordinate plane is divided into four sections by the intersecting x and y axis. As you can see from the image above, these sections are called quadrants. Each quadrant is represented using Roman Numerals like Quadrant I, Quadrant II, Quadrant III and Quadrant IV.

If you want to locate a point on the coordinate plane, you need to look at the ordered pairs which determines the location on the coordinate plane. This can be determined by plotting the x-axis or the first value of the ordered pair along with the y-axis or the second value of the ordered pair. In other words, you can also call them x and y coordinates. Say if you a location at the origin, then the ordered pair can be written as (0,0) because the x and y coordinates are both zero. If you have an x coordinate of 3 and y coordinate of 4, then the ordered pair is (3,4).

To determine the location on a coordinate plane from the point, move vertically down to the right to see where it intersects with the horizontal axis and that is your x-axis and the distance between the origin to the location vertically is your y-axis.

Example 1 – Locate (4, 5) and identify the quadrant.

x coordinate = +4
y coordinate = +5 Example 2 – Locate (-2, 3) Example 3 – Locate (4, -5) 