Triple Integral: Evaluating Limits

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Homework Help Overview

The discussion revolves around evaluating a triple integral of the form ∫∫∫xyz dV over a tetrahedron defined by specific vertices. Participants are focused on determining the correct limits of integration for the variables involved.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to establish the bounds for integration, initially suggesting dzdydx order. There is confusion regarding the correct limits for z and y, with some participants questioning the interpretation of the tetrahedron's geometry.

Discussion Status

Some guidance has been offered regarding the bounds for y and z, with participants exploring different interpretations of the tetrahedron's surfaces. There is ongoing confusion about the correct setup for the integral, indicating a productive exchange of ideas without a clear consensus yet.

Contextual Notes

Participants are grappling with the geometric representation of the tetrahedron and how it affects the limits of integration. There is mention of plotting points to visualize the problem, which suggests a reliance on graphical interpretation to aid understanding.

mvpshaq32
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Homework Statement


Evaluate the triple integral.
∫∫∫xyz dV, where T is the sold tetrahedron with vertices (0,0,0), (1,0,0), (1,1,0), and (1,0,1)

The Attempt at a Solution



I'm having trouble finding the bounds. So far I'm integrating it in order of dzdydx with my x bounds as 0-1, my y bounds as 0-x, but I'm not sure how to find the z bounds.
 
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if you integrate over z first, it will be bounded by function of both z & y, representing the top plane of the tetrathedron
 
mvpshaq32 said:

Homework Statement


Evaluate the triple integral.
∫∫∫xyz dV, where T is the sold tetrahedron with vertices (0,0,0), (1,0,0), (1,1,0), and (1,0,1)


The Attempt at a Solution



I'm having trouble finding the bounds. So far I'm integrating it in order of dzdydx with my x bounds as 0-1, my y bounds as 0-x, but I'm not sure how to find the z bounds.

similarly your y bounds are not y=0 to y=x, but will be y=0 to y=1-x, to see this look at the line formed by the top surface of the tetrahedron in the xy plane
 
lanedance said:
similarly your y bounds are not y=0 to y=x, but will be y=0 to y=1-x, to see this look at the line formed by the top surface of the tetrahedron in the xy plane

Sorry, I'm still confused. How would I integrate over z first?
And I am not seeing the line y=1-x formed. I plotted (0,0,0), (1,0,0), (1,0,1) and (1,1,0) onto a xy graph so the points would be (0,0), (1,0), and (1,1) giving me the line y=x or is that not how I approach it?
 
apologies you are correct, so the integral should be
int^1_0 (int^0_x ( int_0^{f(x,y)} dz) dy ) dx

now you just need to find the upper bound for the first integral f(x,y) which is the upper bounding plane of the tetrahedron.
 

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