If A is 3 x 3 matrix that satisfies A3 = A, thena)A is diagonalizableb...
Statement: If A is a 3 x 3 matrix that satisfies A^3 = A, then A is diagonalizable.
Explanation:
Diagonalization of a matrix refers to the process of finding a diagonal matrix D and an invertible matrix P such that A = PDP^(-1), where D is a diagonal matrix with eigenvalues of A on its diagonal.
To determine if A is diagonalizable, we need to consider its eigenvalues and eigenvectors.
Eigenvalues:
The characteristic polynomial of a matrix A is defined as det(A - λI), where λ is a scalar and I is the identity matrix. The eigenvalues of A are the values of λ that satisfy this characteristic polynomial.
In this case, we have A^3 = A. Let's consider the characteristic polynomial of A:
det(A - λI) = det(A^3 - λI) = det(A^3 - A) = det(A(A^2 - I))
Since A^3 = A, we can simplify the above expression as:
det(A(A^2 - I)) = det(A(A - I)(A + I))
The eigenvalues of A are the values of λ that satisfy det(A(A - I)(A + I)) = 0.
Eigenvectors:
For each eigenvalue λ, the eigenvectors of A are the non-zero vectors x that satisfy the equation Ax = λx.
To determine if A is diagonalizable, we need to check if there are enough linearly independent eigenvectors for each eigenvalue.
Explanation for option A:
If A is a 3 x 3 matrix that satisfies A^3 = A, then we can conclude the following:
- The eigenvalues of A are the values of λ that satisfy det(A(A - I)(A + I)) = 0.
- The eigenvectors of A can be found by solving the equation Ax = λx for each eigenvalue.
Since A satisfies A^3 = A, it follows that the characteristic polynomial of A is different from its minimal polynomial. This implies that A has distinct eigenvalues.
If A has distinct eigenvalues, then it can be diagonalized. This means that there exists an invertible matrix P and a diagonal matrix D such that A = PDP^(-1). Therefore, option A is correct.
If A is 3 x 3 matrix that satisfies A3 = A, thena)A is diagonalizableb...
As given A^{3}=A then A^3-A=0
So A satisfy the polynomial x^3-x=0 and lets it it not the minimal Polynomial then it Either x,(x-1),(x+1) then A is Zero matrix or Identify matrix or -Identity matrix which are Diagonal matrix
if minimal polynomial is x(x-1)(x+1) then A has eigenvalues 0,+1,-1 so its Diagonal
ps- Do x(x+1), x(x-1) and x^2-1 ursellf