Difficulty finding integral answer to set function

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Discussion Overview

The discussion revolves around the computation of a double integral related to a specific set defined within a square. Participants are exploring the limits of integration and the conditions under which the integral is evaluated, focusing on the subset of points defined by certain inequalities.

Discussion Character

  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant proposes a setup for the double integral Q(A) and suggests that their limits of integration may be incorrect, initially arriving at an answer of 1/2.
  • Another participant questions the clarity of the original question, specifically regarding the inclusion of values for x greater than 2/3.
  • A participant clarifies that the upper limit of 2/3 for x is necessary to ensure that y remains less than 1, based on the defined inequalities.
  • Another participant challenges this reasoning, stating that the condition for y does not completely exclude values when x exceeds 2/3, suggesting a need for further clarification on the limits.

Areas of Agreement / Disagreement

Participants express differing views on the limits of integration and the implications of the inequalities, indicating that there is no consensus on the correct interpretation of the problem or the limits of integration.

Contextual Notes

Unresolved issues include the clarity of the original question, the implications of the defined inequalities, and the specific limits of integration for the double integral.

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Note: as i was typing this post, i think i figured out the answer but i want to confirm.
Question:
let A denote the set of points that are interior to, or on the boundary of, a square with opposite verties at the points (0,0) and (1,1). let Q(A) = ∫∫dydx
if C, a subset of A, is the set {(x,y): 0 < x/2 ≤ y ≤ 3x/2 < 1}, compute Q(A)

Solution:
I kept getting 1/2 as the answer, but i think my limits of integration were wrong. is the following correct?

^{2/3}_{0}∫^{3x/2}_{x/2}∫dydx

this setup gives the answer as 2/9... unfortunately i do not have the correct answer which is why i needed to verify.
 
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The question is not completely clear. For x > 2/3 is anything included?
This would involve: x/2 < y < 1.
 
Unfortunately, i typed the question verbatim and not sure how to respond to you.

note that the 2/3 upper limit on x was defined by me. I figured that y <1 (from y ≤ 3x/2 < 1). so therefor x cannot be more than 2/3, since y must also be less than 3x/2. for x> 2/3, y>1. e.g. when x=1, y=3/2.

does that make sense?
 
No. Your condition x/2≤y≤3x/2 for x > 2/3 restricts y to x/2≤y≤1, but does not remove it altogether.
 

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