Linear Algebra: One Solution for a System with Leading 1's?

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Homework Help Overview

The discussion revolves around the properties of a linear system of equations, specifically focusing on the implications of having leading 1's in the reduced row-echelon form of an augmented matrix. Participants are examining whether the presence of n leading 1's guarantees a unique solution.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the definition of leading 1's and their role in determining the uniqueness of solutions. Some express uncertainty about the treatment of leading 1's in the augmented part of the matrix and whether this affects the system's consistency.

Discussion Status

The discussion is active, with participants exploring different interpretations of the definitions and implications of leading 1's in the context of the problem. There is no clear consensus, but various perspectives are being shared, including potential typographical errors in the source material.

Contextual Notes

Some participants note that the book they are referencing does not clearly delineate the augmented matrix, which may contribute to the confusion regarding the definition of leading 1's. This lack of clarity may be influencing their interpretations of the problem.

tgt
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Homework Statement


If a linear system of n equations in n unkowns has n leading 1's in the reduced row-echelon form of its augmented matrix, then the system has exactly one solution.






The Attempt at a Solution


True to me but is it?
 
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tgt said:

The Attempt at a Solution


True to me but is it?
Yes it is, but is this all your attempt to the solution?
 
kof9595995 said:
Yes it is, but is this all your attempt to the solution?

The book said False. Must be a typo?

If there are n equstions and n leading ones, all variables must equal to a specific number. And that is the only solution in the system.
 
Em...unless 1's in the augmented part can be called "leading 1",then the matrix can be like this:
1 0 2
0 0 1
But I have a very vague memory that the 1 in augmented part(1 in second row) can't be called "leading 1",but you should check it out.
 
kof9595995 said:
Em...unless 1's in the augmented part can be called "leading 1",then the matrix can be like this:
1 0 2
0 0 1
But I have a very vague memory that the 1 in augmented part(1 in second row) can't be called "leading 1",but you should check it out.

But there is n leading 1's with n variables. Your example have 2 leading 1's in 3 variables.

The question does say n leading 1's in the reduced echelon matrix. The fact that its reduced echelon suggest that all columns have 0 elsewhere.
 
Kof is right. A leading 1 is a pivot position.

EDIT:

Here:
1 0 2
0 0 1
The 1 in the 2nd row isn't a leading 1, but here it is:
1 0 2
0 1 0
 
tgt said:
But there is n leading 1's with n variables. Your example have 2 leading 1's in 3 variables.

The question does say n leading 1's in the reduced echelon matrix. The fact that its reduced echelon suggest that all columns have 0 elsewhere.

No, my example is an augmented matrix, the 3rd column is the right hand side of the equations.
 
kof9595995 said:
No, my example is an augmented matrix, the 3rd column is the right hand side of the equations.

So you are saying that if a linear system of n equations in n unkowns has n leading 1's in the reduced row-echelon form of its augmented matrix then it is inconsistent. hence the book was right.
 
Personally I don't think 1 in augmented part can not be called leading one, and with roam's confirmation, probably it's just a typo in the book.
 
  • #10
kof9595995 said:
Personally I don't think 1 in augmented part can not be called leading one, and with roam's confirmation, probably it's just a typo in the book.

The book I'm using does not draw a vertical line before the last column even for an augmented matrix. So in that case the book was right, no typo.
 

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