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Homework Help: Differential equations

  1. Mar 18, 2008 #1
    We have these two equations:
    dx/dt = -k1 (y)
    dy/dt = k2 x
    k1= 10 k2= 10
    These are the conditions:
    x(0)= 100
    y(0) = 0

    I am so confused.....This is what I have done so far....but is not making any sense...

    x= (dy/dt) (1/k2)
    Substitute in:

    d2y/dt2 = -100 y

    So the solution is

    Y= c1 cos 10x+ c2 sin 10x

    I don't know how to use boundary counditions now....Is this even a right approach?

    Thank you so much
     
  2. jcsd
  3. Mar 18, 2008 #2
    The rule for a differential equation:
    [tex]\frac{dy}{dt}=ky[/tex]
    [tex]y(t)=y_0e^k^t[/tex]
     
  4. Mar 18, 2008 #3

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    Good so far.

    There is no x in your differential equation; why do you have one here? Try finding the solution to the second order differential equation again.
     
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