Math Problem Statement

Is the matrix [0 5; 1 0] diagonalizable?

Solution

To determine if the given 2×22 \times 2 matrix

A=[0510]A = \begin{bmatrix} 0 & 5 \\ 1 & 0 \end{bmatrix}

is diagonalizable, we proceed as follows:

Step 1: Compute the eigenvalues

The eigenvalues of AA are found by solving the characteristic equation:

det(AλI)=0\det(A - \lambda I) = 0

det[λ51λ]=0\det \begin{bmatrix} -\lambda & 5 \\ 1 & -\lambda \end{bmatrix} = 0

λ2(0)+5=0    λ2=5    λ=±i5\lambda^2 - (0) + 5 = 0 \implies \lambda^2 = -5 \implies \lambda = \pm i\sqrt{5}

Thus, the eigenvalues are λ1=i5\lambda_1 = i\sqrt{5} and λ2=i5\lambda_2 = -i\sqrt{5}, both of which are complex.

Step 2: Diagonalizability

A matrix is diagonalizable if:

  1. It has nn linearly independent eigenvectors (where nn is the size of the matrix).
  2. Its eigenvalues need not be real, but the algebraic multiplicity must equal the geometric multiplicity for each eigenvalue.

For this matrix, the eigenvalues are distinct (i5i5i\sqrt{5} \neq -i\sqrt{5}), and distinct eigenvalues guarantee nn linearly independent eigenvectors.

Conclusion

The matrix AA is diagonalizable. The correct answer is "Yes".

Would you like a step-by-step calculation of eigenvectors or further clarification?


Related Questions:

  1. How do you calculate eigenvectors for a given matrix?
  2. What does it mean for a matrix to have distinct eigenvalues?
  3. Can a matrix with complex eigenvalues be diagonalized in the real number space?
  4. What is the significance of algebraic and geometric multiplicities in diagonalizability?
  5. How does diagonalizability relate to the properties of symmetric matrices?

Tip:

For 2×22 \times 2 matrices, distinct eigenvalues (real or complex) always imply diagonalizability.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Diagonalization
Eigenvalues and Eigenvectors

Formulas

Characteristic equation: det(A - λI) = 0
Quadratic equation: λ^2 + 5 = 0

Theorems

Diagonalizability criterion
Eigenvalue multiplicity

Suitable Grade Level

Undergraduate (Linear Algebra Course)