Solve this vector system containing sum and dot product equations

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Homework Help Overview

The discussion revolves around a vector system involving sum and dot product equations. Participants are exploring the relationships between vectors and the implications of given equations in a potentially two-dimensional or three-dimensional context.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to clarify the nature of the problem, including whether it is in 2D or 3D, and what specific vectors are known or unknown. There are discussions about writing vectors in terms of others and the implications of different assumptions on the solutions.

Discussion Status

The discussion is active, with participants providing various interpretations and questioning the completeness of the information provided. Some guidance has been offered regarding the relationships between the vectors, but there is no explicit consensus on the approach or solution.

Contextual Notes

There are noted constraints regarding the lack of specification about the dimensionality of the problem and the nature of the vectors involved. Participants are also considering the implications of defining certain vectors as constants or variables.

LCSphysicist
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Homework Statement
All below
Relevant Equations
All below
1594813352799.png


Seems to me the answer is a specific vector:

The second forms a plane, while the first X is just a vector. The intersection between the λX that generates the (properties of all vectors that lie in the...) plane (i am not saying X is the director vector!)

How to write this in vector language?
 
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What are you supposed to solve for? The first equation gives ##\vec x## precisely: ##\vec x = \vec u - \vec y##. What more is there to do?
 
LCSphysicist said:
Homework Statement:: All below
Relevant Equations:: All below

View attachment 266376

Seems to me the answer is a specific vector:

The second forms a plane, while the first X is just a vector. The intersection between the λX that generates the (properties of all vectors that lie in the...) plane (i am not saying X is the director vector!)

How to write this in vector language?
You didn't specify whether this is a 2D or 3D problem. You also didn't specify that ##\vec u, ~ \vec v,~ m## are given constants and the unknowns are ##\vec x## and ##\vec y##. Is that correct? Certainly, if it is a 3D problem there can be many solutions. For example if ##\vec v = \langle 0,0,1\rangle## and ##m=0##, so ##\vec x## is perpendicular to ##\vec v## so ##\vec x## can be any vector in the ##xy## plane. Then no matter what ##\vec u## is ##\vec y = \vec u - \vec x## is a solution. So ##\vec u## and ##\vec x ## can be all over the place.
 
The problem is not i didn't specify, the question is really just it.
Seeing the answer, it write x and y in terms of others vectors a and b.
The answers is right to me, but at same time a little biased, as you both said.

1594837952875.png
 
LCSphysicist said:
The problem is not i didn't specify, the question is really just it.
Seeing the answer, it write x and y in terms of others vectors a and b.
The answers is right to me, but at same time a little biased, as you both said.

View attachment 266391
Unless there was more info provided, I see no way to guess this 'solution' is what was wanted. Indeed, I would propose a better 'solution' is to omit ##\vec b## and define a as a unit vector. ##\frac{m\vec v}{|\vec v|^2}+\lambda\hat a##, where ##\vec v.\hat a=0##, generates all solutions of ##\vec x.\vec v=m##.
 

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