The Number Line
We can associate each real number with a point on the number line. The
location of 0 on the number line is called the origin.
Each point on the number line corresponds to a real number.
For example, on the following number line the point A corresponds to the real
number 3 because point A lies 3 units to the left of 0.
The location of a point on the number line is called its coordinate. The
coordinate of point A is 3.
To plot a point means to place a dot at the location of the point on the
number line.
Example 1
Plot the following numbers on a number line: 9, 8, 4.5, 0,
, 2π
Solution
Find the approximate location of each point and place a dot at that point.
Recall that π ≈ 3.14, so 2π
≈ 6.28. Also,
Note: The symbol ≈ means "is approximately equal
to".
