Help Rectangle to Cylindrical coordinate question

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Homework Help Overview

The discussion revolves around setting up a triple integral in cylindrical coordinates for the evaluation of the integral \(\int\int\int_{E} e^z \, DV\), where the region \(E\) is defined by a paraboloid and a cylinder. The surfaces involved are \(z = 1 + x^2 + y^2\) and \(x^2 + y^2 = 5\).

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to establish the limits for \(z\) and \(r\) in cylindrical coordinates, questioning whether \(z\) should be between \(0\) and \(1 + r\) and \(r\) between \(0\) and \(\sqrt{5}\). Some participants suggest that the limit for \(z\) should actually be \(1 + r^2\) instead. There is also a concern about the accuracy of the problem statement regarding the bounding surfaces.

Discussion Status

The discussion is ongoing, with participants clarifying the setup of the integral and questioning the boundaries of the region defined by the surfaces. There is a recognition that the original assumption about the lower boundary for \(z\) may not be valid, and one participant points out that the surfaces may not enclose a region at all.

Contextual Notes

Participants note that the problem does not specify the lower boundary for \(z\), leading to uncertainty in the setup. Additionally, there is a correction regarding the equation of the cylinder, which is crucial for defining the region of integration.

tnutty
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Homework Statement



evaluate : [tex]\int\int\int_{E} e^z DV[/tex]

where E is enclosed by the paraboloid z = 1 + x^2 + y^2 , the cylinder x^2 + r^2 = 5


I just need help setting this up.

I know that theta is between 0 and 2pi

Now is z between 0 and 1 + r ? and r is between 0 and sqrt(5).

Would the iterated integral set up in cylindrical coordinate look like this :
[tex]\int^{2\pi}_{0}[/tex][tex]\int^{\sqrt{5}}_{0}[/tex][tex]\int^{1+r}_{0}e^z dz* r*dr *d\theta[/tex]
 
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Almost. Since the paraboloid is given by [itex]z= 1+ x^2+ y^2[/itex], the limit on z should be [itex]1+ r^2[/itex] not 1+ r.

But have you copied the problem correctly? One of the surfaces bounding the region you give as "[itex]x^2+ r^2= 5[/itex]". Was that supposed to be [itex]x^2+ y^2= 5[/itex]? If so the two surfaces do NOT completely bound a region. In your integrals you seem to be assuming that the lower boundary is z= 0. Is that given?
 
>>but have you copied the problem correctly? One of the surfaces bounding the region you give as x^2 + r^2 = 5.

I'm sorry its was real late, its supposed to be x^2 + y^2 = 5.

>>In your integrals you seem to be assuming that the lower boundary is z= 0. Is that given?

No, I wasn't sure so I assumed that part. It does not specify
 
If that is correct then there is NO region enclosed by those surfaces!
 

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