Solving Absolute Value Equations and Inequalities
Chapter 2, Sections 6
 You must consider the absolute value equations and inequalities that follow to be forms.
That is, "x marks the spot."
In other words, "x" in the absolute value equations and inequalities below may be any algebraic expression.
The "a" is a real number.
 Geometric Interpretation of Absolute Value Equations and Inequalities
Consider a > 0...
Absolute Value 
Solution 
Graphical Solution 
 x  = a 
x = a and x = a 

 x  < a 
a < x < a 

 x  > a 
x < a or x > a 

 Solving Absolute Value Equations and Inequalities
1) Consider a > 0...
 Note: x and y may be expressions.
Absolute Value 
What To Do 
Solution Set 
 x  = a 
Solve the 2 equations x = a and x = a 
{ x  x = a or x = a } 
 x  < a 
Solve the compound inequality a < x < a 
{ x  a < x < a } 
 x  > a 
Solve the 2 inequalities x < a and x > a 
{ x  x < a or x > a } 
 x  =  y  
Solve the 2 inequalities x = y and x = y 
{ x  x = y or x = y } 
Note that the or means union 
2) Consider a < 0...
Remember that the absolute value of anything is always nonnegative:
  x 
0, for any x.
Absolute Value 
What To Do 
Solution Set 
 x  = a 
Observe that there is no nonnegative number ( x ) that can be negative (a < 0 is given). 
The empty set 
 x  < a 
Observe that there is no nonnegative number ( x ) that can be smaller than a negative number (a < 0 is given). 
The empty set 
 x  > a 
Observe that anything nonnegative ( x ) is always bigger that something negative (a < 0 is given). 
All Real numbers 
