Conceptual question--calc 3

riverjib

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Joined
Oct 18, 2006
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11
Hello,

I solved these two problems, but I was wondering if somebody could tell me some trick to know whether to integrate with respect to x first or with respect to y first. I solved both by trial-and error; I tried both ways to see which one gave me the right answer.

11. f(x,y) = x/y over the region in the first quadrant bounded by the lines y = x, y = 2x, x =2.

15. f(u,v) = v - (sqrt)u over the triangular region cut from the first quadrant of the uv-plane by the line u + v = 1.

Again, I have no problem solving double integrals or deciding how to determine the limits of integration; I just want to know if I can tell ahead of time in which order I should be integrating. Does the one with variables as limits of integration always go on the inside?

Thanks!
 
Personally, I'd do it both ways, just for paratice. This will help give you the judgment you seek. YOU will begin to know and to see which way is more convenient -- if any. This will also help you to see that it isn't possible, sometimes.
 
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