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Math Help - Absolute value problem

  1. #1
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    Post Absolute value problem

    Suppose we have this absolute value question | x-3 | = 3 x
    If we solve this question we break it as
    X - 3 = 3 x or -(x - 3) = 3 - x
    Now if we solve it we come to know that the part on right is true for all real numbers
    And the part on the left is true for only 3

    I also have read that if there is a variable on right side of absolute value then we need to verify our solutions.
    Now we have two solution one is 3 and the other one is all real numbers. The first solution works but there is a problem with the second one, Suppose we have a real number 4 and we put it in our absolute value equation

    | x 3 | = 3 x
    | 4 3 | = 3 4
    | 1 | = -1
    Now when we verify our solution we discard the solution not satisfying the equation as in this case the second solution is not satisfying the solution. So, we have only one solution to this equation and that is 3.

    But when I saw the answer of this question in the book I saw that the answer is x < =3

    Now I am confuse please help me.
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  2. #2
    Super Member bigwave's Avatar
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    ....
    Last edited by bigwave; August 23rd 2010 at 03:26 PM. Reason: op out
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  3. #3
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    Brother this is not the answer of my question. the question that i am asking is , as you can see i am breaking the absolute value equation into two equations, when i solve both equations the solution for the first is only 3 and when i solve the second one the solution to this is all real numbers , Now how can we decide that the answer is x < =3. i need the explanation of this with proper method which should be applicable for all such type of problems. Thank you.
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  4. #4
    Super Member bigwave's Avatar
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    why are you using 4 rather a number less than or equal to 3
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