How to expand the span of a vector set in linear algebra?

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Homework Help Overview

The discussion revolves around the concept of vector sets in linear algebra, specifically focusing on how to expand a set of vectors to span R³. The original poster expresses an understanding that a 3x2 matrix does not span R³ and seeks guidance on how to add a vector to achieve this.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the need to add a third vector to a set of two vectors to span R³. There are considerations about linear independence and the criteria for selecting an appropriate third vector. Some participants suggest checking the linear independence of the existing vectors and exploring the determinant of a matrix formed by the vectors.

Discussion Status

The discussion is active, with participants offering various approaches to the problem. There is no explicit consensus on a single method, but multiple lines of reasoning are being explored regarding how to select a third vector and the implications of linear independence.

Contextual Notes

Participants are operating under the constraints of linear algebra principles, particularly regarding vector spaces and spanning sets. The original poster's question reflects a common homework scenario where specific vector sets are analyzed for their spanning capabilities.

wishnight
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Homework Statement


I do understand that in matrix 3x2, the set of vector doesn't span of R3. What should I do to make the set of vector span of R3.


Homework Equations





The Attempt at a Solution


I think adding one more set of vector is the best idea. So, if I can add one more set of vector to make them span of R3, how to find the third set of vector. thanks
 
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I think you need to state the question more clearly. In a 3x2 matrix the columns don't span R^3. The three standard vectors (1,0,0), (0,1,0), (0,0,1) span R^3. I you want to make a matrix of which the colums span R^3 put these in a matrix.

If you want to use the two vectors you already got from the matrix:
- first check to see if the two you have are linearly independent.
i.e. whether one is a mulitple of the other (in the case of 2 vectors)
- If they are find a third vector that is also linearly independt of both the vectors (together)
- I they aren't find two more that, together with one of the vectors you already had,
are linearly independent of each other.

Then put them in a matrix.
 
I mean if we got 2 vector a = (1,2,1) and b = (1,3,1). Then I need to create one more vector that will make the set of vectors span of R3
 
There are many way's to do this. One way is to put these to vectors and (a,b,c) in a matrix. Calculate the determinant then choose a,b,c such that the determinant is not 0. Any such a,b,c will do
 

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