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Evaluating a double integral

  1. Apr 26, 2010 #1
    1. The problem statement, all variables and given/known data

    Evaluate the following double integral:
    ∫ ∫ R sin (x/y) dA

    where R is the region bounded by the y axis, y=pi and x=y^2

    2. Relevant equations

    as in problem statement

    3. The attempt at a solution

    Well I started this question by drawing the area to be evaluated. From this I chose my limits of integration, however I feel this may be where I am going wrong. I used ∫ (upper y=pi lower y=0) dy and ∫ (upper x=y^2 lower x=0) dx.
    Im not sure if this is right first of all, and secondly, sin (x/y) is really tripping me up. This is because when I treat a variable as constant, where is it going. For example if I firstly evaluate sin (x/y) dy, i'm not sure of the result.
     
  2. jcsd
  3. Apr 26, 2010 #2

    tiny-tim

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    Homework Helper

    Hi ilovemath88! Welcome to PF :smile:

    (have an integral: ∫ and a pi: π and try using the X2 and X2 tags just above the Reply box :wink:)

    Yes, your limits, ∫0π0y2 are correct.

    As you say, you have to treat one variable as a constant when you integrate wrt the other …

    so which is easier to integrate first, sin(x/y)dx or sin(x/y)dy ? :wink:
     
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