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Hi, could anyone help me with a algebra question

  1. May 6, 2007 #1
    hi there,

    i just forgot how to solve quadratics and was wondering if anyone could help me on a question it is quite easy.

    (x+3)(x-2)^2= 72
    (x-2)^2
    =x^2-4x+4
    (x+3)(x^2-4x+4)
    x^3-4x^2+4x+3x^2-12x+12

    =x^3-x^2-8x+12= 72

    im not quite sure what i should do next if i havent made any mistakes so far.

    thankyou,
     
  2. jcsd
  3. May 6, 2007 #2

    Office_Shredder

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    Staff Emeritus
    Science Advisor
    Gold Member

    I would start by noting 72=9*8=3*3*8.

    This should get you one solution.

    Then when you get to

    x^3-x^2-8x+12= 72

    Subtract to get

    x3-x2-8x-60=0

    and factor out x-a, where a is the solution you found earlier.
     
  4. May 7, 2007 #3
    Guess factors of 60 to plug in using synthetic division/substitution
     
  5. May 8, 2007 #4
    multiply each term of one binomial by each term of of the other

    (x + 3)(x-2)^2=72

    multiply each term by 3
    3 * -2 = -6
    3 * x = 3x

    combine like terms
    x^2 + x3 - x2 -6

    is

    x^2 + x -6

    now

    x^2 + x -6 + 72

    do the quadratic eq and check for 0
     
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