Is [3, -8, 1], [6, 2, -5] a Basis for R3?

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In summary, The set [3, -8, 1] and [6, 2, -5] is a basis for a plane in R3 because it spans R2, which is a plane in R3, and the two vectors are linearly independent. The linear span of 2 linearly independent vectors is a plane in R^n.
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Homework Statement


Determine whether the set is a basis for R3.

[3, -8, 1] , [6, 2, -5]



The Attempt at a Solution



I know it does not span R3, but the book says it is a basis for a plane in R3. How is it a plane?
 
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It doesn't span R3, but it does span R2, which you can think of as a plane in R3.
 
  • #3
You first have to prove that the 2 vectors are linearly independent. To do that, recall the definition of linear dependence for 2 vectors. What does it mean for 2 vectors to be linearly dependent? If it doesn't satisfy that definition, and if none of the vectors is the zero vector, then you would have 2 linearly independent vectors.

If you have only 1 linearly independent vector, then the linear span of that vector would be a line.

The linear span of 2 linearly independent vectors is a plane in R^n.
 

1. What is a basis for R3?

A basis for R3 is a set of three vectors that are linearly independent and span the three-dimensional space. This means that any vector in R3 can be written as a linear combination of these three vectors.

2. How do I determine if a set of vectors is a basis for R3?

To determine if a set of vectors is a basis for R3, you can use the following criteria:

  • The set must contain three vectors.
  • The set must be linearly independent, meaning none of the vectors can be written as a linear combination of the other vectors.
  • The set must span R3, meaning any vector in R3 can be written as a linear combination of the three vectors.
If these criteria are met, then the set is a basis for R3.

3. What is the significance of the numbers in the vectors [3, -8, 1] and [6, 2, -5]?

The numbers in the vectors represent the coordinates of each vector in a three-dimensional space. The first number represents the x-coordinate, the second represents the y-coordinate, and the third represents the z-coordinate.

4. Can a set of two vectors be a basis for R3?

No, a set of two vectors cannot be a basis for R3. This is because a basis for R3 must contain three linearly independent vectors in order to span the three-dimensional space.

5. What is the importance of having a basis for R3?

Having a basis for R3 allows us to represent any vector in three-dimensional space as a linear combination of the basis vectors. This is useful in many areas of mathematics and science, such as in solving systems of linear equations and in studying three-dimensional objects and phenomena.

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