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Math Help - Just Checking

  1. #1
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    Just Checking

    Im just wondering if some this question is right?

    |7 - x| = 9
    |x| = 9 - 7
    x = 2.

    I was wondering if it would be a negitive 2 or a positive. Thanks!
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by omgitzbella View Post
    Im just wondering if some this question is right?

    |7 - x| = 9
    |x| = 9 - 7
    x = 2.

    I was wondering if it would be a negitive 2 or a positive. Thanks!
    This is not correct. To get rid of the absolute value bars, you need to square both sides of the equation:
    |7 - x| = 9

    |7 - x|^2 = (7 - x)^2 = 81

    You take it from here. (And make sure to check your solutions back in the original equation.)

    -Dan
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  3. #3
    Senior Member DivideBy0's Avatar
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    Think of what 7-x can be if |7-x|= 9.

    Obviously you can have |-9|=9 and |9|=9, so we can have:

    7-x=-9 \Rightarrow x = 16

    or

    7-x=9 \Rightarrow x = -2

    So the solutions are x = 16, -2
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  4. #4
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    Thanks

    Thank you =)
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