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Homework Help: Diff EQ, can't see what I did wrong expressing this seperable

  1. Jan 18, 2006 #1
    Hello everyone. I don't see how this problem is wrong, i never do.
    Here it is:
    Solve the differential equation
    (y^{15} x ){dy}/{dx} = 1 + x.
    Use the initial condition y(1) = 3.
    Express y^{16} in terms of x.
    y^{16} = ?

    y^15*dy = (1+x)/x dx;

    I integrated both sides and got:
    (y^16)/16 = ln(x)+x+c;
    y^16 = 16(ln(x)+x+c);
    3^16 = 16 + c
    C = 43046705

    I submitted this:
    y^{16} = 16*(ln(x)+x+43046705)

    which was inccoret, any ideas? thank u!
  2. jcsd
  3. Jan 18, 2006 #2


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    Homework Helper

    Try y^{16} = 16*ln(x)+16*x+43046705

    also, you may need to put ln(|x|) instead of ln(x).
  4. Jan 18, 2006 #3
    Nicely done benorin that was correct! i done f'ed up! thank you again!
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