Solving an absolut-valued function

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Homework Help Overview

The discussion revolves around solving the absolute value equation |x-4|*x - x = 0. Participants are exploring the implications of the absolute value function and the conditions under which they can manipulate the equation.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Some participants attempt to rearrange the equation to isolate the absolute value, while others question the validity of dividing by x and the implications of x being zero. There is also discussion about how to handle the absolute value in the context of the equation.

Discussion Status

Participants are actively engaging with the problem, sharing various approaches to factor the equation and questioning assumptions about the values of x. There is a recognition of multiple potential solutions, but no explicit consensus on the final values has been reached.

Contextual Notes

There is an ongoing discussion about the inclusion of zero in the set of real numbers and its impact on the solution process. Some participants express confusion about the steps needed to arrive at the final solutions.

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Homework Statement



I have an abs-function |x-4|*x -x = 0

which I need to solve.


The Attempt at a Solution



Do I need to re-arrange so I get

|x-4| = x/x = 1


thus we have x-4 = -1 or x-4 = 1.

Hence x = 3 or x = 5 ?
 
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Science4ver said:

Homework Statement



I have an abs-function |x-4|*x -x = 0

which I need to solve.


The Attempt at a Solution



Do I need to re-arrange so I get

|x-4| = x/x = 1


thus we have x-4 = -1 or x-4 = 1.

Hence x = 3 or x = 5 ?

You unwisely divided by x. You can only do that if x is nonzero. You are missing a possible value for x.
 
Dick said:
You unwisely divided by x. You can only do that if x is nonzero. You are missing a possible value for x.

well in the assigment x belongs to R.

But how do I obtain the final value of x? I am lost here. Any way to remove the abs value ?
 
Science4ver said:
well in the assigment x belongs to R.

But how do I obtain the final of x? I am lost here.

And doesn't R contain 0?
 
mtayab1994 said:
And doesn't R contain 0?

it most certainly does, but what do I do with the equation to obtain the final and third solution?
 
Science4ver said:
it most certainly does, but what do I do with the equation to obtain the final and third solution?

The cleanest way is to factor it into x*(|x-4|-1)=0. How can the product of two numbers be zero?
 
Dick said:
The cleanest way is to factor it into x*(|x-4|-1)=0. How can the product of two numbers be zero?

split x*(l x-4 l -1)=0 into two equations. That should help you even more.
 
mtayab1994 said:
split x*(l x-4 l -1)=0 into two equations. That should help you even more.

I know then x is either zero or x is found by solving |x-4|-1 = 0

cool, thanks !
 
Science4ver said:
I know then x is either zero or x is found by solving |x-4|-1 = 0

cool, thanks !

Great ! And what are the values?
 
  • #10
mtayab1994 said:
Great ! And what are the values?

x = 0 or x = 3 og x = 5?
 
  • #11
Nice job!
 
  • #12
Science4ver said:
x = 0 or x = 3 og x = 5?
Why the question mark? (In both this and your original post.)

What do you get if you put one of those numbers into the original equation?
 
  • #13
HallsofIvy said:
Why the question mark? (In both this and your original post.)

What do you get if you put one of those numbers into the original equation?

They mean nothing. Simply placed them in the wrong place.
 

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