Linear Algebra Exam 3 Flashcards
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Linear Algebra Exam 3 Flashcards

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Questions and Answers

What is a set of vectors said to be if the vector equation x1v1 + x2v2 + ... + xpvp = 0 has only trivial solutions?

Linearly independent

What does it mean if non-trivial solutions exist?

There are infinitely many solutions, indicating a dependent system.

What is a trivial solution?

The zero vector is a solution.

What is a pivot position in a matrix?

<p>A position that contains a leading one after row reduction.</p> Signup and view all the answers

What does it mean for a matrix to be inconsistent?

<p>It has no solutions.</p> Signup and view all the answers

What is a consistent matrix?

<p>A system that has at least one solution.</p> Signup and view all the answers

What indicates that a set of vectors is linearly dependent?

<p>A non-trivial solution exists.</p> Signup and view all the answers

Are standard basis vectors linearly independent?

<p>True</p> Signup and view all the answers

What does the Fundamental Theorem of Linear Algebra Part I state?

<p>dim(Col(A)) + dim(Nul(A)) = n.</p> Signup and view all the answers

What is a basis for a vector space?

<p>A set of vectors that is linearly independent and spans the space.</p> Signup and view all the answers

What is the span of vectors v1, v2,..., vn?

<p>The set of all linear combinations c1v1 + c2v2 + ... + cnvn.</p> Signup and view all the answers

What makes a set of vectors linearly independent?

<p>No vector can be expressed as a linear combination of the others.</p> Signup and view all the answers

What is the dimension of the null space of a matrix A?

<p>It is the number of free variables in the equation Ax = 0.</p> Signup and view all the answers

The dimensions of the column space of A are equal to the rank of A.

<p>True</p> Signup and view all the answers

How do you find the basis set of a matrix A?

<p>Find the rref (A0) and identify the pivot columns.</p> Signup and view all the answers

What defines an eigenvalue of a matrix?

<p>A scalar λ for which there exists a non-trivial solution x in R^n of the equation Ax = λx.</p> Signup and view all the answers

An n x n matrix A is invertible if and only if detA ≠ 0.

<p>True</p> Signup and view all the answers

If a set of p vectors spans a p-dimensional subspace H of R^n, then these vectors form a basis for H.

<p>True</p> Signup and view all the answers

If H is a p-dimensional subspace of R^n, then a linearly independent set of p vectors in H is a basis for H.

<p>True</p> Signup and view all the answers

A matrix is invertible when the determinant is 0.

<p>False</p> Signup and view all the answers

Three vectors, one of which is the zero vector, can form a basis for R^3.

<p>False</p> Signup and view all the answers

The only three-dimensional subspace of R^3 is R^3 itself.

<p>True</p> Signup and view all the answers

An n x n matrix A is diagonalizable if A has n distinct eigenvalues.

<p>True</p> Signup and view all the answers

A set B={v1, v2,..., vn} of vectors is said to be an EIGENBASIS for R^n when there is an n x n matrix A such that B is a set of n linearly independent eigenvectors of A.

<p>True</p> Signup and view all the answers

V1 and v2 are linearly independent eigenvectors of an n x n matrix A then they correspond to distinct eigenvalues of A.

<p>False</p> Signup and view all the answers

If eigenvectors of an n x n matrix A are a basis for R^n, then A is diagonalizable.

<p>True</p> Signup and view all the answers

Study Notes

Linear Independence and Solutions

  • A set of vectors is linearly independent if the equation x1v1 + x2v2 + ... + xpvp = 0 has only the trivial solution (all constants are zero).
  • Non-trivial solutions indicate the existence of infinitely many solutions and the presence of a free variable, suggesting the system is dependent.
  • Trivial solutions refer to the zero vector being a solution in the vector equation.

Matrix Properties

  • Pivot positions in a matrix occur where after row reduction, a leading one is found.
  • An inconsistent matrix has no solutions, while a consistent matrix has at least one solution.
  • A matrix is singular (not invertible) when its determinant equals zero.

Vector Spaces and Basis

  • A basis for a vector space is a set of linearly independent vectors that spans the space.
  • The span of vectors includes all possible linear combinations of those vectors.
  • The standard basis vectors for R^n are linearly independent and correspond to the identity matrix.

Dimension and the Fundamental Theorem

  • The dimensions of the column space (Col(A)) and null space (Nul(A)) of a matrix A satisfy the equation: dim(Col(A)) + dim(Nul(A)) = n.
  • The number of pivot columns from the reduced row echelon form provides a basis for Col(A), while free variables reveal the basis for Nul(A).

Eigenvalues and Diagonalization

  • An eigenvalue (λ) of a matrix A is a scalar such that there exists a non-trivial solution to Ax = λx; corresponding non-trivial solutions are the eigenvectors.
  • A matrix is diagonalizable if it has n linearly independent eigenvectors or can be represented as A = PDP^(-1) with D being a diagonal matrix.

Theorems and Properties

  • The dimensions of the column space equal the rank of A.
  • If a set of p vectors spans a p-dimensional subspace, they form a basis for that subspace.
  • A set is linearly dependent if it contains more vectors than dimensions (p > n) or if it contains the zero vector.

Miscellaneous

  • Geometric multiplicity of an eigenvalue is the dimension of the null space of A - λI, while algebraic multiplicity is the number of times λ appears as a root of det(A - λI) = 0.
  • A system of equations has unique solutions represented in terms of a basis when those solutions lie within a defined subspace.

Truth Statements for Review

  • A matrix A is invertible if its determinant is non-zero.
  • An eigenbasis consists of n linearly independent vectors corresponding to eigenvalues of a matrix.
  • The projection of a vector y on a subspace W remains within W's orthogonal complement (W⊥).

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Test your knowledge with these flashcards covering key concepts from Linear Algebra Exam 3. Learn about linear independence and the implications of trivial versus non-trivial solutions in vector equations. Perfect for reviewing before the exam!

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