Arithmetic/Absolute Values

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Absolute value[edit]

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:

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:

1

|-5|=

2

|9|=

3

|-3.8|=

4

|-139,462|=

5

|5/8|=

6

What is the absolute value of 0?

|0|=

7

Why?

 
Calculate the following:

8

|27|=

9

|-1.9|=

10

|3 - 7|=

11

|3 - 0.5|=

12

abs (-6)=

13

Draw a graph of abs(x) from -5 to +5.

 

14

Can abs(x) ever be less than zero?

yes
no

15

How can you see that from your graph?