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Homework Help: Quadratic equation homework problem

  1. Jan 31, 2008 #1
    1. The problem statement, all variables and given/known data

    y^2 - 2y = x^3 + 2x^2 + 2x + 3

    2. Relevant equations

    3. The attempt at a solution

    Solve for y
    How do you solve for y? my book says since that equation is quadratic in y, it can be solved as y = 1 +- sqrt(x^3 + 2x^2 + 2x + 4) but I have no idea how to do that...

    all I can do is y(y-2) ...
  2. jcsd
  3. Jan 31, 2008 #2


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    Homework Helper

    Can you express [itex]y^2-2y[/itex] in the form [itex]a(y+h)^2+k[/itex]?
  4. Jan 31, 2008 #3
    Thanks for your reply
    y^2 - 2y - K = 0
    -k, -2y
    K = x^3 + ....
    Unfortunately, i seem unable to do so
  5. Jan 31, 2008 #4
    Oh wait, I forgot about completing the square, I got it thanks
  6. Feb 1, 2008 #5


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    Science Advisor

    You can also use the quadratic formula, might be easier.
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