February 7 - Real Numbers and Absolute Value

Today, February 7th, in PreCal 20S, we learned about real number lines.

Every real number corresponds to a point on the real number line. There is a one-one correspondence between real numbers and the points on the line. In this real number line, there are no gaps, the line is complete throughout. Example:
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-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

When Graphing on a Real Number Line - An open dot means that the point does not include the real number. A closed dot means that the point includes the real number.

Absolute Value

Also, today in class, we learned about absolute value.
The absolute value of a real number is the distance from zero to the position of the number on the real number line. When finding the absolute value of a real number, ignore the signs.
The notation for absolute value is x
Example: -2 = 2 , 2 = 2
Example: 2 - -5 , 2 - 5 = -3