1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Easy differential equation but i am stuck

  1. Feb 20, 2012 #1
    1. The problem statement, all variables and given/known data
    What is the general solution of tv' + v = 0?
    book says it is v(t) = c/t but i dont see how
    i tried to solve like this:

    v' + (1/t)v = 0

    p(t) = 1/t
    P(t) = Ln(t)

    y = e^ln(t) + c

    = t + e^c

    please help,thanks

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 20, 2012 #2


    User Avatar
    Homework Helper

    what is y?

    your first equation is separable, write v'=dv/dt, then move all terms with a v to the LHS and all terms with a t to the RHS then integrate both sides
  4. Feb 20, 2012 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    This isn't right. What you're doing by calculating ##e^{\int p(t)\,dt}## is finding an integrating factor, not the solution to the differential equation. Check your textbook to see what you're supposed to do with this factor.

    (Or solve the problem the way lanedance suggested.)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Easy differential equation but i am stuck