Undetermined system with no solutions?

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Homework Help Overview

The discussion revolves around a system of equations represented as { 2x+3y+z-3v=2 ; x-y+2z+v=0 ; 3x+2y+3z-2v=-2}. Participants are exploring whether this system has solutions, noting that it is undetermined due to having more unknowns than equations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the implications of the determinant of a matrix formed from the coefficients of the equations, questioning how linear independence relates to the existence of solutions. There are inquiries about forming a matrix that includes additional vectors and the conditions under which the system may have no solutions.

Discussion Status

The conversation is ongoing, with participants examining different interpretations of linear independence and its connection to the system's solvability. Some guidance has been offered regarding the nature of linear combinations and contradictory statements in the context of the equations.

Contextual Notes

There is mention of a textbook answer stating that the system has no solutions, which prompts further exploration of the reasoning behind this conclusion. Participants are also addressing potential misunderstandings regarding the role of linear independence in determining the existence of solutions.

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So I have the system { 2x+3y+z-3v=2 ;x-y+2z+v=0 ;3x+2y+3z-2v=-2} . I have to show that the system has no solutions.. I notice that it has more unknowns than equations so it is an undetermined system.If I form the matrix ? |(2 1 3 ) (3 -1 2) (1 2 3)| I notice that the determinant is diff from zero so this three vectors are linearly indipendent. Now how do I form a matrix using ( 2 0 -2) and these three vectors with the condition that they have a determinant diff from zero? Because if they have a determinant diff from zero,the system has no solutions.
 
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Elaia06 said:
So I have the system { 2x+3y+z-3v=2 ;x-y+2z+v=0 ;3x+2y+3z-2v=-2} . I have to show that the system has no solutions.. I notice that it has more unknowns than equations so it is an undetermined system.If I form the matrix ? |(2 1 3 ) (3 -1 2) (1 2 3)|
I notice that the determinant is diff from zero so this three vectors are linearly independent.
Right, but what are you deducing from that?
If there are no solutions there must be a linear combination of the equations which eliminates all variables but not all constants. It's fairly easy to spot.
 
I wrote the question in the wrong way..the answer on my textbook is " The system has no solutions"..I just have to show if the system has or not solutions...
 
But if the system has no solutions the vectors forming the matrix including 2 0 -2 should be linearly indipendent /...
 
Elaia06 said:
But if the system has no solutions the vectors forming the matrix including 2 0 -2 should be linearly indipendent /...
Not sure what you mean by 'including 2 0 -2'. Do you mean the 5x3 matrix formed by moving the constants across to the left? The non-existence of solutions does not require all the equations to be linearly independent. Trivial example:
x - 1 = 0
x - 2 = 0
x - 2 = 0
In the OP, I can see a linear combination of the equations which eliminates all the variables but leaves a contradictory statement regarding the constants. That implies there are no solutions.
The det of |(2 1 3 ) (3 -1 2) (1 2 3)| is 0.
 

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