Finding a Basis for Subspace a of R^3

In summary, the question asked for bases for the subspace a of r^3 where y+z=0. The solution involves finding a normal to the plane (0,1,1) and two orthogonal vectors (0,-1,1) and (1,0,0). The book's answer of v=(7,0,0) is incorrect as any vector in R^3 of the form (x,y,-y) would work, making the subspace two dimensional.
  • #1
kwal0203
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0

Homework Statement



Find bases for the following subspace a of r^3

Y+z=0


The Attempt at a Solution



First I found a normal to this plane n=(0,1,1)

Then I found two vectors which are orthogonal to the normal u=(0,-1,1), v=(1,0,0)

Is this correct the answer in my book has v=(7,0,0)

Thanks
 
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  • #2
You are correct. If that is what your book really says it is wrong. Any vector in [tex]R^3[/tex] is of the form (x, y, z). Any vector for which z= -y is of the form (x, y, -y)= (x, 0, 0)+ (0, y, -y)= x(1, 0, 0)+ y(0, 1, -1). Of course, (7, 0, 0) would work as well as (1, 0, 0) but this subspace is definitely two dimensional.
 
  • #3
Great thanks for that. I can see why x=7 works it just confused me why they put that as the only answer @.@
 

1. What is a basis for a subspace of R^3?

A basis for a subspace of R^3 is a set of vectors that can be used to span the entire subspace. This means that every vector in the subspace can be written as a linear combination of the basis vectors.

2. How do you find a basis for a subspace of R^3?

To find a basis for a subspace of R^3, you can use the Gaussian elimination method to reduce the subspace to its simplest form. The nonzero rows of the reduced form will form the basis for the subspace.

3. What is the dimension of a subspace of R^3?

The dimension of a subspace of R^3 is the number of basis vectors needed to span the subspace. This can also be thought of as the number of linearly independent vectors in the subspace.

4. Can a subspace of R^3 have multiple bases?

Yes, a subspace of R^3 can have multiple bases. This is because there are infinitely many ways to choose a set of vectors that can span a subspace. However, all bases for a given subspace will have the same number of basis vectors.

5. Why is finding a basis for a subspace of R^3 important?

Finding a basis for a subspace of R^3 is important because it allows us to represent all vectors in the subspace in a concise and efficient way. It also helps with solving linear systems and understanding the properties of the subspace.

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