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Homework Help: Problem simplifying an equation

  1. Aug 18, 2008 #1
    1. The problem statement, all variables and given/known data
    What is the steps between the two equations?

    2. Relevant equations
    [tex]P = a^{2}P+b^{2}P^{2}/(P+1) \Rightarrow P^{2}-(a^{2}+b^{2}-1)P-b^{2} = 0[/tex]

  2. jcsd
  3. Aug 18, 2008 #2


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    Hi mr.t! :smile:

    i] put the a2P on the left

    ii] multiply both sides by (P + 1) :smile:
  4. Aug 18, 2008 #3
    Hello Tiny-tim!
    Putting the [tex]a^{2}P[/tex] to the left and multiply both sides with (P+1) gives:

    [tex](P+1)(P-a^{2}P) = b^{2}P^{2} \Rightarrow[/tex]
    [tex]\Rightarrow P^{2}-a^{2}P^{2}+P-a^{2}P-b^{2}P^{2} = 0 \Rightarrow[/tex]
    [tex]\Rightarrow P^{2}(1-a^{2}-b^{2})+P(1-a^{2}) = 0[/tex]

    But I still can't come to the final solution? :S
  5. Aug 18, 2008 #4


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    I don't think the two steps are equivalent. Let b=0, then a^2=1 if [tex]P \neq 0[/tex]. Substituting these into the second equation, we have a^2 = 1 only if [tex]P = 0[/tex]
  6. Aug 18, 2008 #5
    It could be an error in the solution then :grumpy: no fun try to learn stuff when you end up spending your time figuring out the imposible...

    thanks for your time anyway!
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