In algebra, being able to identify the coordinates of a point shown on a graph is just as important as being able to plot points. To identify the x-coordinate of a point on a graph, read the number on the x-axis directly above or below the point. To identify the y-coordinate of a point, read the number on the y-axis directly to the left or right of the point. Remember, to write the ordered pair using the correct order (x,y).
example
Name the ordered pair of each point shown:

Solution
Point A is above
−3 on the
x-axis, so the
x-coordinate of the point is
−3. The point is to the left of
3 on the
y-axis, so the
y-coordinate of the point is
3. The coordinates of the point are
(−3,3).
Point B is below
−1 on the
x-axis, so the
x-coordinate of the point is
−1. The point is to the left of
−3 on the
y-axis, so the
y-coordinate of the point is
−3. The coordinates of the point are
(−1,−3).
Point C is above
2 on the
x-axis, so the
x-coordinate of the point is
2. The point is to the right of
4 on the
y-axis, so the
y-coordinate of the point is
4. The coordinates of the point are
(2,4).
Point D is below
4 on the
x−axis, so the
x-coordinate of the point is
4. The point is to the right of
−4 on the
y-axis, so the
y-coordinate of the point is
−4. The coordinates of the point are
(4,−4).
example
Name the ordered pair of each point shown:
Answer:
Solution
Point A is on the x-axis at x=−4 . |
The coordinates of point A are (−4,0) . |
Point B is on the y-axis at y=−2 |
The coordinates of point B are (0,−2) . |
Point C is on the x-axis at x=3 . |
The coordinates of point C are (3,0) . |
Point D is on the y-axis at y=1 . |
The coordinates of point D are (0,1) . |