Triple Integral

  • Thread starter mvpshaq32
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  • #1
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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.
 

Answers and Replies

  • #2
lanedance
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if you integrate over z first, it will be bounded by fucntion of both z & y, representing the top plane of the tetrathedron
 
  • #3
lanedance
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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.
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
 
  • #4
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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?
 
  • #5
lanedance
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apologies you are correct, so the integral should be
[tex] int^1_0 (int^0_x ( int_0^{f(x,y)} dz) dy ) dx[/tex]

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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