Triple Integral: Evaluating Limits

In summary: 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?You first integrate over z by using the quadratic formula. You use the upper bounds for the x and y variables to determine the z bounds.
  • #1
mvpshaq32
28
0

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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  • #2
if you integrate over z first, it will be bounded by function of both z & y, representing the top plane of the tetrathedron
 
  • #3
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
 
  • #4
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?
 
  • #5
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.
 

1. What is the purpose of evaluating limits in triple integrals?

Evaluating limits in triple integrals is important because it helps us determine the volume of a three-dimensional region. By setting limits of integration for each variable, we can calculate the total amount of space enclosed by a given function or surface.

2. How do you determine the limits of integration for a triple integral?

The limits of integration for a triple integral are determined by the boundaries of the three-dimensional region being integrated. This can be done by visualizing the region, plotting it on a graph, or using equations to define its boundaries.

3. Can the order of integration be changed in a triple integral?

Yes, the order of integration can be changed in a triple integral as long as the limits of integration remain the same. However, changing the order may result in a simpler or more complex integration process, depending on the function being integrated.

4. What are some common techniques for evaluating triple integrals?

Some common techniques for evaluating triple integrals include using geometric shapes to visualize the region, converting the triple integral into a series of single or double integrals, and using symmetry to simplify the integral.

5. How does the choice of coordinate system affect the evaluation of a triple integral?

The choice of coordinate system can greatly affect the evaluation of a triple integral. For example, using spherical or cylindrical coordinates can simplify the integral if the region being integrated has a spherical or cylindrical symmetry. However, using the wrong coordinate system can lead to a more complicated integration process.

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