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!

Solving double integral without integrating

  1. Apr 28, 2007 #1
    From an example in my book:

    Int Int (2x) dxdy over R = 0

    (R is the circe x^2+(y-1)^2=1)

    How can one make this conclusion without integrating?
     
  2. jcsd
  3. Apr 28, 2007 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Look at the symmetry. A circle is "symmetric about the origin": If (x,y) is in the circle then so is (-x, -y). That means that for each possible x value, you have the corresponding -x and so the "effect" of the two points will cancel out.
     
    Last edited: Apr 28, 2007
  4. Apr 28, 2007 #3

    Office_Shredder

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It's actually symmetric about (0,1), but you can draw a similiar conclusion to HallsofIvy's post
     
  5. Apr 28, 2007 #4

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Right, sorry about that! If (x. 1+y) is in the circle, so is (-x, 1- y)!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Solving double integral without integrating
Loading...