Linear Algebra - Vectorial Subespaces

In summary, to find the dimension and bases for the vector subspaces U and V, you can use the rank-nullity theorem and the row reduction method. You can also use the properties of vector subspaces to find the dimension and basis for U+V and U ∩ V. To determine if U and V define the same vector subspace, compare their bases and dimensions.
  • #1
encomes
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Homework Statement


It's about Linear Algebra and vector spaces. I've tried it but i can't get the solution...:

In C[tex]^{5}[/tex], the vectorial subespace U generated for (1,2,-1,-1,2), (0,2,-1,0,-2), (00,2,-1,0) and the vectorial subespace V generated for (3,3,0,-5,2), (1,1,0,-3,2), (1,1,0,1,-2).

I have to find a base and the dimension of the vectorial subespaces U, V, U+V and U [tex]\cap[/tex]V. Do U and V define the same vectorial subespace?

Homework Equations


None.

The Attempt at a Solution


I have to find a base and the dimension of the vectorial subespaces U, V, U+V and U [tex]\cap[/tex]V. Do U and V define the same vectorial subespace?

Thank you!
 
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  • #2


Hello! It seems like you are working with two vector subspaces in C^5, U and V. In order to find the dimension and bases for these subspaces, you can use the following steps:

1. To find the dimension of a vector subspace, you can use the rank-nullity theorem, which states that the dimension of a subspace is equal to the rank of its matrix representation minus the nullity (dimension of the null space). In this case, you can represent U and V as matrices and find their ranks and nullities to determine their dimensions.

2. To find a basis for a vector subspace, you can use the row reduction method to put the matrix representation of the subspace in reduced row echelon form. The columns that contain pivots in the reduced matrix will form a basis for the subspace.

3. To find the dimension and basis for U+V, you can use the properties of vector subspaces. Since U+V is the set of all vectors that can be written as a sum of a vector in U and a vector in V, you can find a basis for U+V by combining the bases for U and V. The dimension of U+V will be the sum of the dimensions of U and V.

4. To find the dimension and basis for U ∩ V, you can use the fact that U ∩ V is the set of all vectors that are in both U and V. Therefore, the basis for U ∩ V will be the intersection of the bases for U and V, and the dimension will be the number of vectors in this basis.

5. To determine if U and V define the same vector subspace, you can compare their bases and dimensions. If they have the same basis and dimension, then they define the same vector subspace.

I hope this helps! Let me know if you have any further questions or need clarification. Good luck!
 
  • #3


To find a base for a vector space, we need to find a set of linearly independent vectors that span the space. For U, we can see that the vectors (1,2,-1,-1,2), (0,2,-1,0,-2), and (0,0,2,-1,0) are linearly independent and span U. Therefore, a base for U is {(1,2,-1,-1,2), (0,2,-1,0,-2), (0,0,2,-1,0)} and the dimension of U is 3.

Similarly, for V, the vectors (3,3,0,-5,2), (1,1,0,-3,2), and (1,1,0,1,-2) are linearly independent and span V. So a base for V is {(3,3,0,-5,2), (1,1,0,-3,2), (1,1,0,1,-2)} and the dimension of V is 3.

For U+V, we can see that all the vectors in U and V are linearly independent, so a base for U+V would be the union of the bases for U and V. Therefore, a base for U+V is {(1,2,-1,-1,2), (0,2,-1,0,-2), (0,0,2,-1,0), (3,3,0,-5,2), (1,1,0,-3,2), (1,1,0,1,-2)} and the dimension of U+V is 6.

To find U ∩ V, we need to find the set of vectors that are in both U and V. From inspection, we can see that the vector (1,1,0,0,0) is in both U and V. Therefore, a base for U ∩ V is {(1,1,0,0,0)} and the dimension of U ∩ V is 1.

No, U and V do not define the same vectorial subspace because they have different bases and dimensions. They also have different generating vectors.
 

1. What is a vectorial subspace in linear algebra?

A vectorial subspace is a subset of a vector space that satisfies the three properties of a vector space: closure under addition, closure under scalar multiplication, and the existence of a zero vector. This means that any linear combination of vectors in the subspace will also be in the subspace, and the subspace contains the zero vector.

2. How do you determine if a subset is a vectorial subspace?

To determine if a subset is a vectorial subspace, you must check if it satisfies the three properties of a vector space: closure under addition, closure under scalar multiplication, and the existence of a zero vector. If all three properties are satisfied, then the subset is a vectorial subspace.

3. What is the dimension of a vectorial subspace?

The dimension of a vectorial subspace is the number of linearly independent vectors in the subspace. This can also be thought of as the minimum number of vectors needed to span the subspace.

4. How do you find a basis for a vectorial subspace?

To find a basis for a vectorial subspace, you can use the process of Gaussian elimination to reduce the vectors in the subspace to their row-echelon form. The non-zero rows in the resulting matrix will form a basis for the subspace.

5. Can a vectorial subspace contain infinite vectors?

Yes, a vectorial subspace can contain infinite vectors. For example, the subspace of all polynomials of degree 3 or less contains infinite vectors, as there are an infinite number of possible coefficients for each term in the polynomial.

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