Determining 3D Vector Basis with a,b,c Vectors

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SUMMARY

The discussion focuses on determining if the vectors a = (2, -3, 2), b = (1, 1, -1), and c = (8, 5, -2) can form a basis for R^3. Participants suggest using the dot product and scalar triple product to assess linear independence. The conclusion is that since the dot product of the cross product of vectors a and b with vector c yields a non-zero result (18), the vectors cannot serve as a basis for R^3. A reminder is provided that three linearly independent vectors are required to form a basis.

PREREQUISITES
  • Understanding of vector operations, specifically dot product and cross product
  • Knowledge of linear independence in the context of vector spaces
  • Familiarity with the definition of a basis in R^3
  • Concept of the scalar triple product and its properties
NEXT STEPS
  • Learn how to compute the scalar triple product for three vectors
  • Study the properties of linear independence in vector spaces
  • Explore the geometric interpretation of basis vectors in R^3
  • Review examples of linearly independent and dependent vectors
USEFUL FOR

Students studying linear algebra, educators teaching vector spaces, and anyone interested in understanding the concepts of basis and linear independence in three-dimensional space.

kevykevy
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Homework Statement


Determine whether the the vectors a = (2, -3,2), b = (1, 1, -1) and
c = (8, 5, -2) can be used as a basis for vectors in R^3 (3D space)


Homework Equations





The Attempt at a Solution


I really have no clue, I think maybe you use either cross product, dot product or triple scalar product...?
 
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kevykevy said:
I think maybe you use either cross product, dot product or triple scalar product...?

Why don't you try one of these? I'd use the dot product first, to show whether or not the vectors are mutually orthogonal.
 
kevykevy said:

Homework Statement


Determine whether the the vectors a = (2, -3,2), b = (1, 1, -1) and
c = (8, 5, -2) can be used as a basis for vectors in R^3 (3D space)

What's the definition of a basis?
 
cristo said:
Why don't you try one of these? I'd use the dot product first, to show whether or not the vectors are mutually orthogonal.

They don't have to be mutually orthogonal to be linearly independent, and it is unlikely that they will be. To kevykevy: You were on the right track with the scalar triple product. What properties of this product do you know?
 
LeonhardEuler said:
They don't have to be mutually orthogonal to be linearly independent, and it is unlikely that they will be. To kevykevy: You were on the right track with the scalar triple product. What properties of this product do you know?

Sorry, I read "orthogonal" that wasn't in the question!
 
cristo said:
Sorry, I read "orthogonal" that wasn't in the question!

I know what you're talking about. I've been there more than a few times myself. :redface:
 
Cross Product
a x b = (1, 4, 5)

Dot Product
(1, 4, 5) x (8, 5, -2) = 18

Since 18 doesn't equal 0, then the vectors cannot be used as basis vectors

is that right?
 
to radou - basis vectors, example i, j, and k with the carot(^) on top
 
kevykevy said:
to radou - basis vectors, example i, j, and k with the carot(^) on top

Ok, that's an example of a basis. We can add that every set consisting of three linearly independent vectors forms a basis for R^3. All you have to do is check if your vectors are linearly independent.
 
  • #10
And if you are going to be doing problems like this it would be a really good idea for you to look at the definition of "basis" in your textbook.
 

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