Arithmetic/Absolute Values

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:



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 }

{ abs (-6)={ 6_7 }
 * type="{}"}

{Draw a graph of abs(x) from -5 to +5.
 * type="{}" coef="2"}

{Can abs(x) ever be less than zero? -yes +no
 * type=""}

{How can you see that from your graph?
 * type="{}" coef="2"}
 * /Answers to "Why" and graphical questions/