Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Differential Equation

  1. Jan 11, 2009 #1
    I'm trying to solve this firrst order diff. equation, where I'm given the initial value, x(0)=2





    this is as far as I got, do I sub in x(0)=2 into the LHS? if not, could i have some pointers to help carry on?

    Last edited: Jan 11, 2009
  2. jcsd
  3. Jan 11, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Your solution looks good up until the final line. You may want to re-check your integrals.
  4. Jan 11, 2009 #3
    [edit] - there should be 'dt' s on the RHS in the 2nd and 3rd line of work
  5. Jan 11, 2009 #4


    User Avatar
    Science Advisor

    [tex]\int \frac{dt}{\sqrt{t}}= \int t^{-1/2}dt[/tex]
    is NOT [itex]ln(t^{1/2})[/itex]!
  6. Jan 11, 2009 #5
    also dont forget your constant that comes from the integration
  7. Jan 12, 2009 #6
    oh right, my mistake lol

    so, the last line should be


    I have no idea where to go from here with the initial value that I was given x(0)=2! would I sub in x=2 into the equation?
  8. Jan 12, 2009 #7


    User Avatar
    Science Advisor
    Homework Helper

    As other people have been trying to tell you, the integral of t^(-1/2) DOES NOT involve a log. It's just power law. And I still don't see a constant of integration.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook