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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!
     
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