1. Not finding help here? Sign up for a free 30min 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!

Need help solving a differential equation

  1. Jan 25, 2010 #1
    1. The problem statement, all variables and given/known data

    dy/dx = 2y + x^2 + 5.

    This is a linear differential equation, so I know I need to use the definition of it which is y*e^integral(P(x)) dx = integral(f(x)*e^int(P(x)) dx.


    I tried to get it into this form, so I tried to change the equation to dy/dx + -2y = x^2 + 5. Eventually, the right side of my linear equation for solving becomes the integral of (x^2 + 5)*e^-2x dx. The 5e^-2x dx is easy to integrate, but x^2*e^-2x dx is not. Did I form my initial equation correctly or am I really supposed to find the integral of that?
     
  2. jcsd
  3. Jan 25, 2010 #2

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Use integration by parts twice to integrate x2e-2x.
     
  4. Jan 25, 2010 #3
    Yeah, I figured it out after looking at it for a while. Thank you.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook