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Sunday, 24 March 2013

Intermediate Algebra chapter 2 part 5


Solving Absolute Value Equations and Inequalities
Chapter 2,
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 InequalitiesConsider a > 0...
Absolute
Value

Solution
Graphical
Solution
| x | = ax = -a and x = a
| x | < a-a < x < a
| x | > ax < -a or x > a

Solving Absolute Value Equations and Inequalities1) Consider a > 0...
Note: x and y may be expressions.
Absolute
Value
What
To Do
Solution
Set
| x | = aSolve the 2 equations
x = -a and x = a
{ x | x = -a or x = a }
| x | < aSolve the compound inequality
-a < x < a
{ x | -a < x < a }
| x | > aSolve 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 non-negative:
| x |  0, for any x.
Absolute
Value
What
To Do
Solution
Set
| x | = aObserve that there is no non-negative number (| x |) that can be negative(a < 0 is given).The empty set
| x | < aObserve that there is no non-negative number (| x |) that can be smaller than a negative number (a < 0 is given).The empty set
| x | > aObserve that anything non-negative (| x |) is always bigger that something negative (a < 0 is given).All Real numbers
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