Mathematics » Introducing Graphs » Use the Rectangular Coordinate System

# Identifying Points on a Graph

## Identifying Points on a Graph

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 $$\left(x,y\right).$$

## Example

Name the ordered pair of each point shown:

### Solution

Point A is above $$-3$$ on the $$x\text{-axis},$$ so the $$x\text{-coordinate}$$ of the point is $$-3.$$ The point is to the left of $$3$$ on the $$y\text{-axis},$$ so the $$y\text{-coordinate}$$ of the point is $$3.$$ The coordinates of the point are $$\left(-3,3\right).$$

Point B is below $$-1$$ on the $$x\text{-axis},$$ so the $$x\text{-coordinate}$$ of the point is $$-1.$$ The point is to the left of $$-3$$ on the $$y\text{-axis},$$ so the $$y\text{-coordinate}$$ of the point is $$-3.$$ The coordinates of the point are $$\left(-1,-3\right).$$

Point C is above $$2$$ on the $$x\text{-axis},$$ so the $$x\text{-coordinate}$$ of the point is $$2.$$ The point is to the right of $$4$$ on the $$y\text{-axis},$$ so the $$y\text{-coordinate}$$ of the point is $$4.$$ The coordinates of the point are $$\left(2,4\right).$$

Point D is below $$4$$ on the $$x-\text{axis},$$ so the $$x\text{-coordinate}$$ of the point is $$4.$$ The point is to the right of $$-4$$ on the $$y\text{-axis},$$ so the $$y\text{-coordinate}$$ of the point is $$-4.$$ The coordinates of the point are $$\left(4,-4\right).$$

## Example

Name the ordered pair of each point shown:

### Solution

 Point A is on the x-axis at $$x=-4$$. The coordinates of point A are $$\left(-4,0\right)$$. Point B is on the y-axis at $$y=-2$$ The coordinates of point B are $$\left(0,-2\right)$$. Point C is on the x-axis at $$x=3$$. The coordinates of point C are $$\left(3,0\right)$$. Point D is on the y-axis at $$y=1$$. The coordinates of point D are $$\left(0,1\right)$$.

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