Volumes with triple integrals, aka I suck at geometry

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Homework Help Overview

The problem involves calculating the volume of a solid bounded by several planes, specifically defined by the equations x+y-z = 0, y-z = 0, y+z = 0, and x+y+z = 2. The subject area relates to geometry and calculus, particularly in the context of triple integrals.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss variable substitutions and the implications for setting up the integral. There are questions about determining the correct inequalities for the new boundaries after substitution. Some participants suggest finding the vertices of the solid to better understand its shape.

Discussion Status

The discussion is ongoing, with participants exploring different approaches to set up the integral correctly. Some guidance has been offered regarding the order of operations in setting up the problem, but there is no explicit consensus on the best method yet.

Contextual Notes

There appears to be uncertainty regarding the initial setup of the integral and the implications of variable substitution. Participants are also reflecting on their understanding of the geometric aspects of the problem.

Gauss M.D.
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Homework Statement



Calculate the volume of the body that is bounded by the planes:

x+y-z = 0
y-z = 0
y+z = 0
x+y+z = 2

Homework Equations





The Attempt at a Solution



I made a variable substitution

u = y+z
v = y-z
w = x

which gave me the new boundaries

u+w = 2
v+w = 0
v = 0
u = 0

Problem is, I must have slept late the day they taught this is class. What do I do to determine which way these inequalities go?!?
 
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Gauss M.D. said:

Homework Statement



Calculate the volume of the body that is bounded by the planes:

x+y-z = 0
y-z = 0
y+z = 0
x+y+z = 2

Do you think you need calculus?

$$z=x+y \\ z= -x -y +2 \\ z=y \\ z=-y$$

That should be pretty simple...:-p
 
You should not change variables before you have set up the integral. Do that first.
 
To get an idea of the shape, try to find the vertices.
 

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