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!

Homework Help: A double integral problem

  1. Oct 30, 2013 #1
    The problem statement, all variables and given/known data
    [tex]∫∫x^4ydxdy[/tex]
    x [-5,10]
    y [-1,1]
    (don't know how to do a definite integral in the math code...)

    The answer choices are
    [itex]A)10^5[/itex]
    [itex]B)0[/itex]
    [itex]C)-10^{10}[/itex]

    The attempt at a solution
    [itex]\frac{x^5y}{5}[/itex] evaluated at -5 to 10.

    then
    [itex]∫20625ydy[/itex] evaluated at -1 to 1.

    My final answer is 20625. What did I do wrong?
     
  2. jcsd
  3. Oct 30, 2013 #2

    Mark44

    Staff: Mentor

    Your integral above is OK, but you fouled up when you evaluated the integrand. Try again.
     
  4. Oct 30, 2013 #3
    I see. 0. thanks
     
  5. Oct 30, 2013 #4
    Just fyi, to do a definite integral it's \int_{#}^{#} the _{#} being the bottom number, ^{#} being the top number.
     
  6. Oct 30, 2013 #5

    Mark44

    Staff: Mentor

    So the full integral would look like this:
    Code (Text):
    $$ \int_{-1}^1 \int_{-5}^{10} x^4 y dx~dy$$
    I put this inside HTML code tags so that you could see the script without the browser rendering it. In rendered form, it looks like this:
    $$ \int_{-1}^1 \int_{-5}^{10} x^4 y dx~dy$$
     
  7. Oct 30, 2013 #6
    Oh ok good to know. Thanks guys!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Loading...