411 REFERENCE · Wikibooks
Arithmetic/Absolute Values
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Absolute value
The absolute value of a number is found by applying a simple rule: If you see a negative sign in front of the number, change it to a plus sign. If you see a plus sign, leave it alone. So, for example, the absolute value of -17 is +17. The absolute value of +36 is +36.
Another way to understand the absolute value of a number is to think about the number line:
image:Real_Number_Line.PNG
The absolute value of a number is the distance from zero to that number on the number line.
The absolute value of x is usually written as |x|. On calculators and computers it is sometimes written as abs (x).
{Questions: (note: if you don't see an answer box, do it on paper)}
{Calculate the absolute value of the following numbers:}
{
|type="{}"}
|-5|={ 5_7 }
{
|type="{}"}
|9|={ 9_7 }
{
|type="{}"}
|-3.8|={ 3.8_7 }
{
|type="{}"}
|-139,462|={ 139,462|139462_7 }
{
|type="{}"}
|5/8|={ 5/8|0.625_7 }
{What is the absolute value of 0?
|type="{}"}
|0|={ 0_7 }
{Why?
|type="{}" coef="2"}
{Calculate the following:}
{
|type="{}"}
|27|={ 27_7 }
{
|type="{}"}
|-1.9|={ 1.9_7 }
{
|type="{}"}
|3 - 7|={ 4_7 }
{
|type="{}"}
|36| - |-11|={ 25_7 }
{
|type="{}"}
|3 - 0.5|={ 2.5_7 }
{
|type="{}"}
abs (-6)={ 6_7 }
{Draw a graph of abs(x) from -5 to +5.
|type="{}" coef="2"}
{Can abs(x) ever be less than zero?
|type="()"}
-yes
+no
{How can you see that from your graph?
|type="{}" coef="2"}
||/Answers to "Why" and graphical questions/