Understanding N in Jordan Block Matrix

In summary, the question asks to show that the characteristic polynomial of any Jordan block J is equal to 0. This can be done by substituting J into its own characteristic polynomial, which is equivalent to setting all the diagonal entries of N (the matrix whose (i,j) entry is δi,j-1) to 0.
  • #1
Wildcat
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Homework Statement



Let J be any Jordan block, i.e. J =λI + N where N is the matrix whose (i,j) entry is δi,j-1.
PJ(λ) is J's characteristic polynomial. Show that PJ(J)=0.

Homework Equations





The Attempt at a Solution



I don't understand what this part of the question means → N is the matrix whose (i,j) entry is δi,j-1. Can someone explain? Does it mean that for example the (2,2) entry of N would be the (2,1) entry of J which would be 0? Making the diagonal entries of N all =0??
 
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  • #2
Wildcat said:

Homework Statement



Let J be any Jordan block, i.e. J =λI + N where N is the matrix whose (i,j) entry is δi,j-1.
PJ(λ) is J's characteristic polynomial. Show that PJ(J)=0.

Homework Equations





The Attempt at a Solution



I don't understand what this part of the question means → N is the matrix whose (i,j) entry is δi,j-1. Can someone explain? Does it mean that for example the (2,2) entry of N would be the (2,1) entry of J which would be 0? Making the diagonal entries of N all =0??


I don't know how to close threads, but while I was waiting for a reply i figured it out!
 

What is linear algebra?

Linear algebra is a branch of mathematics that deals with the study of vector spaces and linear transformations between them. It involves the use of matrices and systems of linear equations to solve problems related to lines, planes, and higher dimensional objects.

What are Jordan blocks?

Jordan blocks are square matrices with a particular form, where all the entries above the main diagonal are equal to 1, and the remaining entries are all 0. They are often used in linear algebra to represent linear transformations that are not diagonalizable.

How are Jordan blocks used in linear algebra?

Jordan blocks are used in linear algebra to represent the Jordan canonical form, which is a way to classify and simplify the structure of matrices. They are particularly useful in solving systems of differential equations and in finding eigenvalues and eigenvectors of matrices.

What is the significance of Jordan blocks?

The significance of Jordan blocks lies in their ability to represent non-diagonalizable linear transformations. This means that even if a matrix cannot be reduced to a diagonal form, it can still be represented using Jordan blocks, which helps simplify calculations and analysis.

What are some real-world applications of linear algebra and Jordan blocks?

Linear algebra and Jordan blocks have many applications in fields such as physics, engineering, computer science, and economics. They are used to solve problems related to optimization, data analysis, image and signal processing, and control systems. For example, they are used in computer graphics to rotate and scale images, and in economics to analyze supply and demand curves.

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