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Homework Help: Find a and b

  1. Nov 3, 2012 #1


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    1. The problem statement, all variables and given/known data
    If [itex]x_1,x_2[/itex] are the roots of [itex]x^2-3x+a=0[/itex] and [itex]x_3,x_4[/itex] are the roots of the equation [itex]x^2-12x+b=0[/itex] and [itex]x_1,x_2,x_3,x_4[/itex] are in increasing G.P., find a and b

    2. Relevant equations

    3. The attempt at a solution
    [itex]x_1+x_2=3 \\
    x_1x_2=a \\
    x_3+x_4=12 \\

    But these are not sufficient to find a and b. Also what is meant by an increasing G.P.?
  2. jcsd
  3. Nov 3, 2012 #2


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    G.P. = Geometric Progression

  4. Nov 3, 2012 #3
    It means that the common ratio of the GP is greater than 1.
  5. Nov 4, 2012 #4


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    This means that [itex]x_1<x_2<x_3<x_4[/itex]
    But what is the use of this in my question?
  6. Nov 4, 2012 #5


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    Ignoring that detail for the moment, simply try answer the question and then you'll see.
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