Math Problem Statement

Let V be a vector space and let A: V -+ V be a linear map. Let A E R. Let VA be the subspace of V generated by all eigenvectors of A having A as eigenvalue. Then every non-zero element of VA is an eigenvector of A having A as eigenvalue.

Solution

The statement provided deals with eigenvectors, eigenvalues, and subspaces in the context of linear maps in vector spaces. Let's break it down step by step.

  1. Context:

    • VV is a vector space, and A:VVA: V \to V is a linear map.
    • λR\lambda \in \mathbb{R}, so λ\lambda is a real number (presumably an eigenvalue of AA).
    • VλV_\lambda is defined as the subspace of VV generated by all eigenvectors of AA corresponding to the eigenvalue λ\lambda. Mathematically, we can define this subspace as: Vλ={vV:A(v)=λv for some v0}.V_\lambda = \{ v \in V : A(v) = \lambda v \text{ for some } v \neq 0 \}.
  2. Restatement of the claim:
    The statement claims that "every non-zero element of VλV_\lambda is an eigenvector of AA having λ\lambda as eigenvalue."

  3. What is this subspace VλV_\lambda?
    The subspace VλV_\lambda consists of all linear combinations of eigenvectors corresponding to λ\lambda. If v1,v2,,vnv_1, v_2, \dots, v_n are eigenvectors corresponding to the eigenvalue λ\lambda, then any element of VλV_\lambda will be a linear combination of these vectors: v=c1v1+c2v2++cnvn,v = c_1 v_1 + c_2 v_2 + \cdots + c_n v_n, where c1,c2,,cnRc_1, c_2, \dots, c_n \in \mathbb{R}.

  4. Proof or verification of the statement:
    We need to show that any non-zero element of VλV_\lambda is an eigenvector corresponding to the eigenvalue λ\lambda.

    Let vVλv \in V_\lambda be a non-zero element. By definition, vv is a linear combination of eigenvectors corresponding to the eigenvalue λ\lambda. Thus, for some eigenvectors v1,v2,,vnv_1, v_2, \dots, v_n and scalars c1,c2,,cnc_1, c_2, \dots, c_n, we have: v=c1v1+c2v2++cnvn.v = c_1 v_1 + c_2 v_2 + \cdots + c_n v_n. Since each viv_i is an eigenvector of AA corresponding to λ\lambda, we know: A(vi)=λvifor all i.A(v_i) = \lambda v_i \quad \text{for all } i. Now, applying AA to the linear combination vv, we get:

    = c_1 A(v_1) + c_2 A(v_2) + \cdots + c_n A(v_n) = c_1 \lambda v_1 + c_2 \lambda v_2 + \cdots + c_n \lambda v_n = \lambda (c_1 v_1 + c_2 v_2 + \cdots + c_n v_n) = \lambda v.$$ Therefore, $$A(v) = \lambda v$$, which shows that $$v$$ is an eigenvector corresponding to the eigenvalue $$\lambda$$.

Thus, the statement is true: every non-zero element of VλV_\lambda is an eigenvector of AA with λ\lambda as the corresponding eigenvalue.


Do you want further details or have any questions?

Here are some related questions to deepen your understanding:

  1. How are generalized eigenvectors defined, and how do they relate to the subspace VλV_\lambda?
  2. What happens if AA has complex eigenvalues? How does the subspace structure change in VV?
  3. Can you describe the geometric multiplicity and algebraic multiplicity of an eigenvalue? How do they relate to the dimension of VλV_\lambda?
  4. What is the significance of the eigenspace VλV_\lambda in the diagonalization of a matrix?
  5. How does the Jordan canonical form involve the subspace VλV_\lambda?

Tip: In linear algebra, eigenvectors and eigenvalues are crucial in simplifying linear transformations, particularly through diagonalization and understanding invariant subspaces.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Vector Spaces
Eigenvalues and Eigenvectors

Formulas

v = c_1 v_1 + c_2 v_2 + ... + c_n v_n (linear combination of eigenvectors)
A(v) = λ v (eigenvalue equation)

Theorems

Eigenvalue theorem
Linear combination of eigenvectors

Suitable Grade Level

Undergraduate level (Linear Algebra)