A **coordinate plane** is a plane that is used to locate points by using coordinates $\left(x, y\right)$ that give the distance from the $x$-axis and the $y$-axis. The coordinate plane is formed by the intersection of the ** x-axis**, a horizontal number line, and the

**, a vertical number line. The axes are perpendicular and intersect at the**

*y*-axis**origin**, which is the point with coordinates $(0, 0)$.

Each location or point in the coordinate plane can be written as an **ordered pair**, which is a pair of numbers written in order, $\left(x, y\right)$, that can be used to locate a point in the coordinate plane. The ** x-coordinate** is the first value in the ordered pair, which determines the horizontal distance of a point from the origin. The

**is the second value of the ordered pair, which determines the vertical distance of a point from the origin.**

*y*-coordinateTo graph a point, begin at the origin. If the $x$-coordinate is negative, move left. If it is positive, move right. If the $y$-coordinate is negative, move down. If it is positive, move up.

### Plotting Ordered Pairs

$(4, 6)$ | $(-3, 4)$ | $(-2, -5)$ |
---|---|---|

From the origin, move 4 units right and 6 units up. | From the origin, move 3 units left and 4 units up. | From the origin, move 2 units left and 5 units down. |

The signs of the coordinates determine which quadrant the point lies in. A **quadrant** is one of four regions of the coordinate plane that are formed by the $x$- and $y$-axis. The quadrants are numbered I, II, III, and IV. Quadrant I is above the $x$-axis and to the right of the $y$-axis, where both coordinates are positive. From there, the quadrants are labeled counterclockwise around the origin.

- In Quadrant I, $x$ is positive, and $y$ is positive.
- In Quadrant II, $x$ is negative, and $y$ is positive.
- In Quadrant III, $x$ is negative, and $y$ is negative.
- In Quadrant IV, $x$ is positive, and $y$ is negative.