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!

Does this method make sense written down this way?

  1. Dec 10, 2011 #1
    1. The problem statement, all variables and given/known data

    Solve the differential equation: [tex]\frac{d^2y}{dx^2}=3x^2-10x+3[/tex]

    3. The attempt at a solution

    [tex]\int\int \frac{d}{dx}\frac({dy}{dx})3x^2-10x+3=\frac{1}{4}x^4-\frac{5}{3}x^3+\frac{3}{2}x^2+c[/tex]

    Does that make sense mathematically?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 10, 2011 #2

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    No. Not even if you fix the parentheses.

    [itex]\displaystyle\int\frac{d}{dx}\left(\frac{dy}{dx} \right)dx=\int\left(3x^2-10x+3\right)dx[/itex]

    [itex]\displaystyle\frac{dy}{dx}=x^3-5x^2+3x+C_1[/itex]

    So that: [itex]\displaystyle y=\int\left\{\int\frac{d}{dx}\left( \frac{dy}{dx} \right)dx\right\}dx=\int\left(x^3-5x^2+3x+C_1\right)dx[/itex]
    which has an additional constant of integration.​
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Does this method make sense written down this way?
  1. Does this make sense? (Replies: 4)

Loading...