Solving an absolut-valued function

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In summary, the conversation is about finding the solution for an absolute value function |x-4|*x -x = 0. The attempt at a solution involved re-arranging the equation and obtaining two values for x (x = 3 or x = 5). However, it was pointed out that the solution was incomplete as it did not include the possibility of x = 0. The conversation then discusses ways to factor the equation and obtain the third solution, with the final values being x = 0, x = 3, and x = 5.
  • #1
Science4ver
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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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  • #2
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.
 
  • #3
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 ?
 
  • #4
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?
 
  • #5
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?
 
  • #6
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?
 
  • #7
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.
 
  • #8
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 !
 
  • #9
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.
 

FAQ: Solving an absolut-valued function

What is an absolute value function?

An absolute value function is a mathematical function that returns the distance of a number from zero on a number line. It can also be thought of as the positive value of a number, regardless of its sign.

How do you solve an absolute value function?

To solve an absolute value function, you can follow these steps:
1. Set up two equations, one with the positive value inside the absolute value bars and one with the negative value inside.
2. Solve each equation separately for the variable.
3. Write the two solutions as a compound inequality using "or" to connect the two equations.

What is the difference between solving an absolute value function algebraically and graphically?

Solving an absolute value function algebraically involves using equations and mathematical operations to find the solution, while solving it graphically involves plotting points on a graph and visually identifying the solution.

Can an absolute value function have more than one solution?

Yes, an absolute value function can have more than one solution. In fact, it can have an infinite number of solutions depending on the values of the variable and the equation.

How do you check if a solution to an absolute value function is correct?

To check if a solution to an absolute value function is correct, you can substitute the value into the original equation and see if it satisfies the equation. If the absolute value of the solution is equal to the value inside the absolute value bars, then the solution is correct.

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