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Help with this separable differential equation

  1. Jan 19, 2013 #1
    The problem is dx/dt = (x+9)^2.
    This is separable so I made it dx / (x+9)^2 = dt.
    The only method I can think of using for something like this is partial fraction, but I can't get it to work with A/(x+9) + B/(x+9).
    Can anyone find a method that works?
  2. jcsd
  3. Jan 19, 2013 #2
    FYI, the partial fraction decomposition would be [itex]\frac{A}{(x+9)}+\frac{B}{(x+9)^2}[/itex].

    This aside, you can simply use the idea of the power rule for integration. What is the integral of 1/u2, for example?
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