Iterated Integrals bounded by curves

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Discussion Overview

The discussion revolves around evaluating the iterated integral \int\int_{Q}\left(1 - x^{3}\right)y^{2} dA, where Q is defined by the curves y=x^2 and x=y^2. Participants explore the appropriate limits of integration and the order of integration.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant proposes the limits of integration as \int^{1}_{0}\int_{\sqrt{y}}^{y^{2}}\left(1 - x^{3}\right)y^{2} dx dy, questioning the correctness of this selection.
  • Another participant asserts that the order of integration dxdy is correct but points out that \sqrt{y} is greater than y^2.
  • A participant expresses confusion about determining the limits of integration and seeks guidance for future reference.
  • Another participant suggests that either \sqrt{y} is less than y^2 or vice versa for every y in the interval, prompting the use of specific values of y to clarify the relationship.
  • There is a suggestion that algebraic manipulation of the inequality could help resolve the confusion regarding the limits.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct limits of integration or the order of integration, indicating that multiple competing views remain regarding the setup of the integral.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the relationships between the curves and the need for clarity on the inequalities involved in determining the limits of integration.

braindead101
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Evaluate [tex]\int[/tex][tex]\int_{Q}\left(1 - x^{3}\right)y^{2} dA[/tex] where Q is the region bounded by y=x^2 and x = y^2

So I have drew the graphs of y=x^2 and x=y^2 and found that they intersect at (0,0) and (1,1). Now I am confused what to replace Q with, but I think it should be this: please tell me if I am incorrect in my selection.

[tex]\int^{1}_{0}[/tex][tex]\int_{\sqrt{y}}^{y^{2}}\left(1 - x^{3}\right)y^{2} dx dy[/tex]

or should I be integrating w.r.t y first? also have I mixed up the y^2 and the sqrt(y) in the limit of integration?
 
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dxdy is correct, but sqrt(y) > y^2.
 
how would i know this for future reference, i am having serious trouble with the limit of integration part.
 
Well, it's clear that either [itex]\sqrt{y} < y^2[/itex] for every y in that interval, or [itex]y^2 < \sqrt{y}[/itex] for every y in that interval, correct?

So, if you try one actual value of y in that interval...


A little algebra would solved it too: what happens if you manipulate that inequality to put all of the y's on the same side?
 

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