Graphing Points in Four Quadrants Identify the x-axis and y-axis. Identify the four quadrants of a coordinate plane. Plot ordered pairs.

Review: Number Line Recall that you learned about the basic number line at the beginning of the school year: You were also introduced to zero and negatives, which completed the number line: What if we take a second number line, turn it upright, and cross the original number line at zero?

Axes & Quadrants The two number lines, when drawn like this, are called “axes”. The horizontal number line is called the “x-axis” and the vertical number line is the “y-axis”. The axes intersect at zero, referred to as the “origin”. They divide the plane into four sections called “quadrants”. The quadrants are labeled with Roman numerals, starting at the positive x-axis and going around counterclockwise.

Good Graph vs. Bad Graph When creating a graph on paper, it is very important that you use a ruler, even when using grid paper. Label the x- and y-axes.

Graphing Points Writing coordinates Rules Tips An ordered pair (x,y) gives the coordinates of the location of a point. The ordered pair (0,0) is the origin. Rules The first number is the x-coordinate; it tells you the number of horizontal units a point is from the origin. The second number is the y-coordinate; it tells you the number of vertical units a point is from the origin. Tips Remember that x comes before y in the alphabet. You walk to the elevator before you ride it up or down.

Follow the Signs + - + - Quadrant II (-x, y) (left, up) Quadrant I (x, y) (right, up) - + Quadrant III (-x, -y) (left, down) Quadrant IV (x, -y) (right, down) -

Example 1 Using your ruler, draw and label the x- and y-axis. Then, plot the point A(5, 2). Step 1: Start at the origin, where the axes intersect. Step 2: Count to the right five units on the x-axis.

The point (5, 2) is in Quadrant I! …continued Step 3: Count up two units (parallel to the y-axis). Step 4: Draw and label the point. A The point (5, 2) is in Quadrant I!

Now You Try! Plot the point B(4, -5) and determine in which quadrant it is located. Plot the point C(-3, -1) and determine in which quadrant it is located.

Answer to #1 Step 1: Start at the origin. Step 2: Count to the right four units on the x-axis. Step 3: Count down five units parallel to the y-axis. Step 4: Draw and label point B. B The point (4, -5) is in quadrant IV!

Answer to #2 Step 1: Start at the origin. Step 2: Count to the left three units on the x-axis. Step 3: Count down one unit Step 4: Draw and label point C. parallel to the y-axis. C The point (-3, -1) is in quadrant III!