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

Trouble completing the square on the integral

  1. Dec 6, 2011 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    3. The attempt at a solution
    The negative sign in front of x^2 is giving me trouble.

    When i complete the square i get; [itex]\sqrt{}-x^2-4x+4 -4[/itex]

    There's some algebra that i don't understand.
  2. jcsd
  3. Dec 6, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    First, complete the square for [itex]x^2+4x\,.[/itex] Then take the negative of the result.
  4. Dec 7, 2011 #3


    User Avatar
    Science Advisor

    [itex]-x^2- 4x= -(x^2+ 4x)[/itex]

    Now complete the square for [itex]x^2+ 4x[/itex].
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook