Inequality absolute value help

In summary: Glad to help.In summary, to solve the inequality ## x - |x-|x|| > 2 ##, you need to consider two cases: when x is greater than or equal to 0, the inequality simplifies to x > 2, and when x is less than 0, the inequality simplifies to x > 2/3. The solution set is where these two inequalities intersect, giving the final answer of x > 2.
  • #1
converting1
65
0
## x - |x-|x|| > 2 ##

how would I go about solving something like this?

my initial thoughts was to consider if x >= 0

I get 2-x < 0 then x > 2 in that case

then consider if x < 0 which I get -|x+x| > 2-x then 2x > 2-x then x > 2/3 but I'm having troubles deciding which one is correct, and if there is another way to do it (I can't seem to sketch |x-|x||

edit: I know it's pretty obvious from looking at the equation that x > 2, but just wondering why I get the x >2/3 part from, and if I got given a question which is not obvious, then how would I know x > 2/3 would be wrong (for example), and which inequality would be the correct bit
 
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  • #2
You do need to consider cases, and your first bit is correct since, if [itex] x \ge 0 [/itex], the absolute value term gives
[tex]
| x - |x|| = |x - x| = 0
[/tex]

and your problem reduces to [itex] x > 2 [/itex].

For the case [itex] x < 0 [/itex], remember [itex] |x| = -x [/itex], so
[tex]
|x - |x|= |x - (-x)| = |2x| = \text{ what?}
[/tex]

Simplify remembering [itex] x < 0 [/itex]: then take that simplification and plug into your original inequality statement and see what happens.
 
  • #3
statdad said:
You do need to consider cases, and your first bit is correct since, if [itex] x \ge 0 [/itex], the absolute value term gives
[tex]
| x - |x|| = |x - x| = 0
[/tex]

and your problem reduces to [itex] x > 2 [/itex].

For the case [itex] x < 0 [/itex], remember [itex] |x| = -x [/itex], so
[tex]
|x - |x|= |x - (-x)| = |2x| = \text{ what?}
[/tex]

Simplify remembering [itex] x < 0 [/itex]: then take that simplification and plug into your original inequality statement and see what happens.

## |x - |x|= |x - (-x)| = |2x| = -2x ## if x < 0

plugging this in I get x - (-2x) > 2 so x > 2/3
 
  • #4
Ok, so for the inequality to be satisfied you need to have both [itex] x > \frac 2 3 [/itex] and [itex] x > 2 [/itex] true. Where on the number line do those two inequalities intersect (where do their graphs overlap)? The answer to that gives the solution set to the problem.
 
  • #5
x>2 obviously! So stupid

thanks, lol.
 
  • #6
"So stupid"

Not at all. At some time we've all benefited from a little push to look at a problem with a different eye.
 

Related to Inequality absolute value help

1. What is the concept of inequality absolute value?

Inequality absolute value is a mathematical concept that refers to the distance between a number and zero on the number line. It is expressed as the absolute value of the difference between the two numbers, regardless of their signs.

2. How do you solve inequality absolute value equations?

To solve inequality absolute value equations, you must first isolate the absolute value expression. Then, you can rewrite the equation as two separate equations, one with a positive value and one with a negative value. Solve both equations separately to find the solutions.

3. What are the properties of inequality absolute value?

The properties of inequality absolute value include the fact that the absolute value of any number is always positive, and the absolute value of a negative number is equal to the positive value of that number. Additionally, the absolute value of a sum is less than or equal to the sum of the absolute values of the individual numbers.

4. How is inequality absolute value used in real life?

Inequality absolute value is used in various real-life situations, such as measuring the difference in temperatures, calculating distances between two points, and determining the difference in values of assets or debts. It is also used in statistics to measure the variability of data.

5. What is the relationship between inequality absolute value and geometric distance?

The relationship between inequality absolute value and geometric distance is that the absolute value of the difference between two numbers on the number line is equal to the distance between those two numbers. This can be visualized by representing the numbers as points on a number line and measuring the distance between them.

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