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What do I do when the first column of my characteristic equation for finding eigenvectors are zero?

$$A=\begin{pmatrix} 2 &4 &1\\ 6 &5 &2\\ 3& 1& 0\end{pmatrix}$$ I got the eigenvalues to be $-2,3,-1$ and I've gotten the eigenvectors of the first $2$ eigenvalues. I'...
Glasstablegirl's user avatar
-3 votes
1 answer
49 views

Finding characteristic polynomial of a square matrix and how to proving that matrix is diagonalizable [closed]

Let $A$ be a square matrix of order $n$ such that $|A + I| = |A − 3I| = 0$ and also $\operatorname{rank}(A)= 2$. I need to find characteristic polynomial of $A$ and have prove that $A$ is ...
Denis Lutsenko's user avatar
1 vote
1 answer
104 views

Given Ker(T) and Ker(T-2I), is T diagonalizable?

I'm stuck on this problem that I found on my book of linear algebra. Be $T:\mathbb{R}ˆ3 \rightarrow \mathbb{R}ˆ3$ a linear map such that $$Ker(T-2I) = \{(x,y,z) | x+y=0\} $$ and $$Ker(T) = \{ (x,y,z)|...
Sof002's user avatar
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1 answer
153 views

Showing $\lambda I_V$ diagonalizable and has only one eigenvalue

Problem: Let $V$ be a finite-dimensional vector space, and let $\lambda$ be any scalar. For any ordered basis $\beta$ for $V$, prove that $[\lambda I_V]_{\beta}=\lambda I$. Then compute the ...
user avatar
0 votes
0 answers
37 views

The eigenspaces of a matrix

I have a list of vectors $v_1, \cdots, v_m \in \mathbb{R}^n$ with $v_i \not=0$ and i'm trying to better understand the eigenspaces of the matrix $M = v_1 {v_1}^T + \cdots + v_m v_m^T$, which is ...
Carles Gelada's user avatar
0 votes
1 answer
113 views

how to solve this third degree characteristic polynomial?

(this exercise is like the previous question I've written today, but now I have a 3-by-3 matrix (with a real parameter $k$). I need to say where the matrix could be diagonalized, if it's possible. (...
Gabriel Burzacchini's user avatar
2 votes
0 answers
43 views

Prove $n\times n$ matrix with uniform random elements is diagonizable?

Let $X$ be a $n\times n$ matrix with $n\in\mathbb{N}^{+}$ and all off diagonal elements of $X$ following a uniform distribution $x_{ij}\sim\mathcal{U}(0,1)$ for any $i,j\in\{1,...,n\}$ with $i\neq j$. ...
user avatar
0 votes
1 answer
92 views

Are the matrices diagonalizable in the field $K$?

I want to check if the following matrices are diagonalizable in the field $K$. (a) $A=\begin{pmatrix}2 &1 & 0 \\ 0 & 2 & 0 \\ 0 & 0 & 2\end{pmatrix}, \ K=\mathbb{C}$ (b) $A=\...
Mary Star's user avatar
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1 vote
1 answer
46 views

$n× n$ matrix being non diagonalisable.

If you let $n$ be greater than or equal to $2$ and let $M$ be an $n×n$ matrix with minimal and characteristic polynomial equal to $(x-a)^n$ for some $a$ in the reals. Why would this not be ...
LozzaG's user avatar
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1 vote
2 answers
40 views

Diagonalization of a particular matrix

I want to prove the following fact: let $A$ be a non-zero square matrix (matrix of an endomorphism in some basis) whose column vectors are the same, i.e. $A = \begin{pmatrix} a_1 & \dots & ...
Uri Toti's user avatar
  • 533
2 votes
1 answer
66 views

rank of $E_i$ in the sum $A=\lambda_1E_1+\dots+\lambda_kE_k$ where $\lambda_i$ are all the eigenvalues of A.

I'm trying to solve the following exersice. Let $A$ be a $\nu\times\nu$ matrix with elements over a field $F$ and let $\chi_A(x)=(-1)^\nu(\lambda_1-x)^{\sigma_1}\dots(\lambda_k-x)^{\sigma_k}$ be the ...
Mathitis's user avatar
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0 votes
2 answers
1k views

$A$ is diagonalizable if the minimal and characteristic polynomial of $A$ are equal.

Problem: The square real matrix $A$ is diagonalizable if the minimal and characteristic polynomial of $A$ are equal. I think I've got this figured out if I can say that the characteristic polynomial ...
user avatar
2 votes
1 answer
24 views

Finding the power of a complex valued matrix with only the characteristic polynomial

Hi I have this question here. Suppose that $A \in M_4(\mathbb{C})$ has the characteristic polynomial $$p_A(x)=(x^2+3)(x^2+\sqrt{3}x+3)$$ Find $A^{12}$. I get my eigenvalues are $\frac{-\sqrt{3}+3i}{...
Future Math person's user avatar
0 votes
4 answers
364 views

Exercise on expression with matrices using Cayley-Hamilton theorem

For the following matrix $$A= \begin{bmatrix} 0 & 1 & 0\\ 1 & 0 & 1\\ 0 & 1 & 1 \end{bmatrix} $$ I need to use the Cayley-Hamilton theorem to calculate $(A+I_3)^{10}(A-I_3)^2+A$...
user avatar
1 vote
1 answer
74 views

For which integer values of n is the matrix diagonalizable by a real matrix?

I need to find the values of n for which matrix C is diagonalizable by a real matrix. $$ C=\begin{pmatrix} 1 & 1\\ n & n + 1\\ \end{pmatrix} $$ I've calculated the characteristic polynomial $...
mathsy's user avatar
  • 11
0 votes
1 answer
145 views

Proving a matrix is diagonalizable given the characteristic polynomial.

If we are given a real symmetric 2x2 matrix how can we deduce that it is diagonalizable given that we know the characteristic polynomial?
ChumBot's user avatar
6 votes
1 answer
493 views

If $A,B$ are diagonalisable, does $AB$ diagonalisable imply $BA$ diagonalisable?

As discussed in this other post, $AB$ and $BA$ always have the same characteristic polynomial, but not necessarily the same minimal polynomial. This means that $AB$ diagonalisable does not imply $BA$ ...
glS's user avatar
  • 7,653
0 votes
4 answers
35 views

Characteristic polynomial in $\mathbb{C}^2$

Consider a finite-dimensional vector space $V$ over a field $\mathbb{F}$.Let $a,b\in\mathbb{F}$. State whether the following is true or not: If $\begin{pmatrix} b & a \\ 0 & b \end{pmatrix}$ ...
user avatar
-1 votes
2 answers
68 views

diagonalize the following n×n matrix. I am wondering if my solution for the characteristic polynomial is valid or if there is a better way to do it.

The following is the question: The following is my answer.
Justin Falconer's user avatar
1 vote
2 answers
81 views

Diagonalizability of a matrix

Show that $$ A :=\begin{pmatrix} 1 & 0 & 0 \\ -2 & 1 & 2 \\ -2 & 0 & 3 \end{pmatrix}$$ is diagonalizable. What I did: First, I determined the characteristic polynomial $$\...
marymk's user avatar
  • 635
0 votes
1 answer
172 views

Drawing conclusions from a characteristic polynomial

I was given a characteristic polynomial and was asked to draw some conclusions from it, but i need some help with figuring something out. My polynomial is this : $\lambda^4 -3\lambda^3 +\lambda^2 +3\...
Notoriousphd's user avatar
1 vote
3 answers
663 views

Let $A$ be a $3\times 3$ matrix with characteristic polynomial $x^3-3x+a$, for what values of $a$ given matrix must be diagonalizable.

Let $A$ be a $3\times 3$ matrix with characteristic polynomial $x^3-3x+a$. For what values of $a$ given matrix must be diagonalizable. I am talking about diagonalizability over reals. Efforts: If a ...
Shweta Aggrawal's user avatar
2 votes
4 answers
957 views

If square matrix A satisfying $A^2-4A+4I=0$ does it follow that A is diagonizable?

I am given the following statement and asked to determine whether it is true or false: If $A$ is an $n\times n$-matrix, and $A^2-4A+4I=0$, then $A$ is diagonizable. Any help is appreciated, thank ...
Filip's user avatar
  • 497
1 vote
3 answers
204 views

Diagonalizing a particular $3\times3$-matrix.

Trying to diagonalize the matrix: $$A=\begin{pmatrix}2 & -\frac{1}{2} & -\frac{1}{2} \\-\frac{1}{2} & 3 & -\frac{1} {2} \\-\frac{1}{2} & -\frac{1}{2} & 5\end{pmatrix},$$ I ...
Charlene's user avatar
  • 697