Kernel, Range, Basis (linear algebra)

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Discussion Overview

The discussion revolves around determining the kernel and range of a linear transformation T from R³ to R², as well as finding a basis for each. Participants explore the definitions and properties related to the kernel and range in the context of linear algebra.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant initially states the transformation T(x,y,z) = (x,y,z) and claims the kernel is {(r, -r, 0)} and the range is R², but expresses uncertainty about finding a basis.
  • Another participant corrects the transformation to T(x,y,z) = (x + y, z) and asks for ideas on the basis.
  • A participant clarifies that a basis is associated with a subspace, prompting further discussion about the kernel and range.
  • It is suggested that the kernel consists of vectors of the form (x, -x, 0), leading to the conclusion that {(1, -1, 0)} is a basis for the kernel.
  • Participants agree that the range is all of R², with the standard basis {(1, 0), (0, 1)} proposed as a basis for the range.
  • One participant notes the dimensions of the kernel, range, and domain, stating that dim Ker(T) is 1, dim Range(T) is 2, and dim Domain(T) is 3.

Areas of Agreement / Disagreement

Participants generally agree on the form of the kernel and range, as well as the bases for each. However, there was initial confusion regarding the transformation and its implications, which was clarified through the discussion.

Contextual Notes

There was some initial ambiguity regarding the transformation definition, which led to corrections and clarifications about the kernel and range. The discussion reflects varying levels of understanding about the concepts of basis and spanning sets.

Codexmac
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Hey all!
I am working on this and got confused. Any help at all would be much appreciated!

Determine the kernel and range of the transformation T and find a basis for each: T(x,y,z)=(x,y,z) from R3 to R2.

I have found the kernel to be the set {(r, -r, 0)}.
Range is R2.
I"m not sure how to find the basis. Any ideas? I think the range is right but not sure.
Thanks guys!
 
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The transformation your have written maps R^3->R^3.
 
Sorry the transformation is T(x,y,z) = ( x + y, z) Any ideas what the basis is?
 
What do you mean basis of a transformation? A basis is something associated with a subspace.
 
He means a basis for the kernel and a basis for the range.

So you have found the range to be all of R^2, then you may give any basis for R^2, recall a basis is a set of vectors from the space such that they are linearly independent and span the space. There is a standard basis for R^2 you may use here...

Similarly, you have characterized all the vectors in the kernel by r*(1,-1,0), where r is any number in R, think about the definition of spanning a space: a set of vectors spans a space if any vector from the space can be expressed as a linear combination of those vectors. So now can you tell me what is the basis you have found for the kernel?
 
Codexmac said:
Sorry the transformation is T(x,y,z) = ( x + y, z) Any ideas what the basis is?
The kernel consists of all (x,y,z) such that T(x,y,z)= (x+y, z)= (0, 0). That is, x+y= 0 or y= -x and z= 0. Any vector in the kernel is of the form (x, -x, 0)= x(1, -1, 0) and so {(1, -1, 0)} is a basis for that one-dimensional vector space.

The range consists of all numbers of the form (x+y, z). Since x and y can be any numbers, so can x+y. The range is all of R2 and so has {(1, 0), (0, 1)} as basis.

Notice that the two dimensions, 1 and 2, add to 3, the dimension of R3.
 
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Okay that makes sense. Thanks guys! The basis is the standard basis of {(1,0),(0,1)} And the range can be any number in R2.
and yes the dim Ker(T) is 1, dim Range(T) is 2, dim Domain(T) is 3.
 

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