What Does 1<= x^2 + y^2 + z^2 <= 25 Look Like in 3-D?

  • Context: Undergrad 
  • Thread starter Thread starter karen03grae
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Discussion Overview

The discussion revolves around the geometric interpretation of the inequality 1 <= x² + y² + z² <= 25 in three-dimensional space. Participants explore the nature of the shapes defined by this inequality, focusing on the concept of spheres and their properties.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant proposes that the region described by the inequality might represent a sphere with a radius between 1 and 25, expressing confusion about how this could be possible.
  • Another participant clarifies that the inequality actually describes the volume between two concentric spheres with radii 1 and 5, centered at the origin.
  • A subsequent reply confirms the idea of the volume between the two spheres, seeking clarification on the terminology used regarding the surfaces of spheres.
  • Further clarification is provided that spheres are closed surfaces and do not have walls, as they are hollow.

Areas of Agreement / Disagreement

Participants generally agree on the interpretation of the inequality as describing the volume between two spheres, though there is some initial confusion regarding the terminology and properties of spheres.

Contextual Notes

There is a potential ambiguity in the interpretation of the term "walls" in relation to the surfaces of spheres, which may require further clarification.

karen03grae
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Problem: Describe what 1<= x^2 + y^2 + z^2 <= 25
looks like in 3-d

Guess: A sphere with a radius between 1 & 25? Don't see how that's possible though...help
 
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Nope,it's the volume (the totality of points) comprised between 2 concentric spheres of radii 1 & 5 with centers at the origin of the coordinate system...

Daniel.
 
WOW! two spheres? Okay. So its the volume between their walls?
 
EXACTLY.But spheres are closed surfaces...They don't have walls,because they're hollow...

Daniel.
 

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