Volumes with triple integrals, aka I suck at geometry

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SUMMARY

The discussion focuses on calculating the volume of a solid bounded by the planes defined by the equations x+y-z=0, y-z=0, y+z=0, and x+y+z=2. A variable substitution was attempted with u=y+z, v=y-z, and w=x, leading to new boundaries of u+w=2, v+w=0, v=0, and u=0. Participants emphasized the importance of establishing the integral before changing variables and suggested finding the vertices of the solid to better understand its shape.

PREREQUISITES
  • Understanding of triple integrals in calculus
  • Familiarity with geometric interpretations of planes
  • Knowledge of variable substitution techniques
  • Ability to determine inequalities from plane equations
NEXT STEPS
  • Study the process of setting up triple integrals for volume calculations
  • Learn how to find the vertices of polyhedra defined by plane equations
  • Explore variable substitution methods in multivariable calculus
  • Review inequalities and their geometric implications in three-dimensional space
USEFUL FOR

Students and educators in calculus, particularly those focusing on multivariable calculus and geometric interpretations of integrals, as well as anyone seeking to improve their understanding of volume calculations in three dimensions.

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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