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Math Help - algebra

  1. #1
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    algebra

    Here is an equation that will always equal 10 when x is a number from 2-9

    but why?



    ( [ (2x + 4)x ] - x) 5
    ------------------
    x
    Last edited by Change72; September 4th 2008 at 04:29 PM.
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  2. #2
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    try again ...

    \frac{([(2x+4)x]-x)5}{x} = 25 when x = 1
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  3. #3
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    whatsthe correct equation?

    i just realized its wrong too
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  4. #4
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    Found my mistake.

    The bottom X should be 2x
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  5. #5
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    still doesn't work ...

    when x = 1, the expression = 12.5
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  6. #6
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    I just corrected the equation. but why does it always equal 10
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  7. #7
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    Quote Originally Posted by Change72 View Post
    Here is an equation that will always equal 10 when x is a number from 2-9

    but why?



    ( [ (2x + 4)x ] - x) 5
    ------------------
    x
    still doesn't work ...

    when x = 2

    \frac{([(2x+4)x]-x)5}{x} = \frac{70}{2} = 35
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  8. #8
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    Quote Originally Posted by skeeter View Post
    still doesn't work ...

    when x = 2

    \frac{([(2x+4)x]-x)5}{x} = \frac{70}{2} = 35
    dude, no.

    the bottom of the equation is 2x

    2*2 = 4
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  9. #9
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    how are you getting 70? i dont follow
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  10. #10
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    Dude, I quoted your last expression.

    doesn't matter anyway ... 70/4 is not equal to 10.

    go find out what the actual expression is ... be sure to test it before you post.
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  11. #11
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    \frac{([(2x+4)x]-x)5}{2x}



    that should be the equation
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  12. #12
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    Maybe I am writing the equation wrong, but this is how it should go.


    X times 2 plus 4

    multiply that by X

    divide that by 2X

    substract X from the answer found above

    multiply that by 5

    should get 10

    dividing by 2x is included in the brackets. Maybe thats why you are confused.
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  13. #13
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    Quote Originally Posted by Change72 View Post
    Maybe I am writing the equation wrong, but this is how it should go.


    X times 2 plus 4

    multiply that by X

    divide that by 2X

    substract X from the answer found above

    multiply that by 5

    should get 10

    this is your expression ...

    \left[\frac{(2x+4)x}{2x} - x\right]5

    note that in the fraction part, the x's cancel, leaving

    \left[\frac{2x+4}{2} - x\right]5

    now divide 2x+4 by the 2 ...

    \left[(x+2) - x\right]5

    the x's in the [brackets] cancel ...

    [2]5 = 10
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  14. #14
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  15. #15
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    so we are done here? thanks a lot.
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