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Simplify to quadratic form

  1. Apr 16, 2008 #1
    can someone show how to simplify [tex]\frac{12x+9}{x} = x+9[/tex] so that it is in the quadratic form: x^2 -3x -9 = 0

    multiplying both sides by x, subtracting both sides by 9 etc. . doesnt give me the quadratic.
     
  2. jcsd
  3. Apr 16, 2008 #2

    tiny-tim

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    Hi alpha01! :smile:

    erm … I think you put 9 on the right-hand side instead of 9x. :redface:
     
  4. Apr 16, 2008 #3
    Just multiply both sides by 'x' :

    ( x (12x + 9 ) ) / x = x ( x + 9 )

    multiplied x on the left hand side cancels out with its denominator & by expanding the right hand side you will get;

    12x + 9 = x^2 + 9x

    Subtracting both sides by (12x + 9);

    0 = x^2 +9x - 12x - 9

    which means;

    x^2 - 3x - 9 = 0

    & thats what you are looking for...
     
  5. Apr 16, 2008 #4

    thanks
     
  6. Apr 17, 2008 #5
    Your welcome !!! :)
     
  7. Apr 17, 2008 #6
    how would he get a quadratic then :confused:
     
  8. Apr 17, 2008 #7
    sorry misread and now i can't delete
     
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