Linear Algebra - Find unit vector orthogonal to 2, 4-space vectors?

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Homework Help Overview

The discussion revolves around finding a unit vector that is orthogonal to two given vectors in four-dimensional space. The vectors provided are u = (2, 0, 1, -4) and v = (2, 3, 0, 1). Participants explore the concept of orthogonality and the conditions required for a vector to be a unit vector.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the definition of orthogonality through the dot product and express uncertainty about how to find a vector that meets both orthogonality and unit length conditions. Some suggest using the Gram-Schmidt process, while others question its applicability given their current knowledge. There are attempts to set up equations based on the conditions for orthogonality and unit length, leading to discussions about variable elimination and matrix forms.

Discussion Status

The discussion is active, with participants sharing their thoughts on how to approach the problem. Some have offered hints and suggestions, while others are working through the implications of their equations. There is a recognition that multiple approaches can be taken, and participants are encouraged to explore different methods without reaching a definitive conclusion yet.

Contextual Notes

Participants mention that they have not yet learned certain methods in class, such as Gram-Schmidt, and express a desire for guidance. There is also a discussion about the number of equations needed to solve for the unknowns, with some participants questioning the validity of setting variables to zero in order to simplify the problem.

  • #31
yes yes, you are right once again!

I'm sorry, I make lots of mistakes at 4:40 am xD
I wanted to do this homework so badly so I must get it done!
 
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  • #32
its fine, happens to everyone
 
  • #33
In order to solve for specific values of a, b, c, and d, you would need four equations. But the problem said "Find any unit vector orthogonal to both of them". Just as, in three dimensions, there are an infinite number of unit vectors orthogonal to a single vector, in four dimensions there are an infinite number of unit vectors orthogonal to two vectors.

In order that (a, b, c, d) be orthogonal to u = (2, 0, 1, -4) and v = (2, 3, 0, 1) we must have, as you say, 2a+ c- 4d= 0 and 2a+ 3b+ d= 0. Subtracting the first equation from the second, 3b- c+ 5d= 0 so c= 3b+ 5d. Put that back into either of the first two equations and you can solve for a in terms of b and d. That gives every vector that is orthogonal to u and v in terms of b and d.
 

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