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Rearranging equation

  1. May 1, 2010 #1
    1. The problem statement, all variables and given/known data

    I need to find t in the following:
    σ = ωi*t + ½ α*t2 (this is ment to be t squared)

    2. Relevant equations

    3. The attempt at a solution
    I got:
    t + t(squared) = 2 * σ/(ωi * α)

    is this then simply
    t = sqrt(2 * σ/(ωi * α)) ??
  2. jcsd
  3. May 1, 2010 #2
    σ = ωi*t + ½ α*t^2
    You can't write this as:
    t + t^2 = 2 * σ/(ωi * α)
    You can't divide only 1 half of the equation by something... then you'll just change it.
    Like dividing by 1/2 a would give:
    t^2 + 2ωi/a*t = 2σ/a
    You just can't simplify it like you do.
    And your third step is not correct either.

    This is a Quadratic Equation ( http://en.wikipedia.org/wiki/Quadratic_equation ), look up how to solve these (you could make use of the quadratic formula).
  4. May 1, 2010 #3
    Quadratic Formula:
    [PLAIN]http://dl.dropbox.com/u/4645835/MATH/Quadratic.gif [Broken]
    Last edited by a moderator: May 4, 2017
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