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OpenStudy (anonymous):

Matrix question

OpenStudy (anonymous):

OpenStudy (anonymous):

sorry dont do matrix graphing :P

OpenStudy (anonymous):

LOL

OpenStudy (anonymous):

R u there?

OpenStudy (anonymous):

HUH how did u get those equations?

OpenStudy (anonymous):

What question r u reading?

OpenStudy (anonymous):

I accidentally posted the wrong question but then I deleted it an reposted the right one

OpenStudy (anonymous):

recheck it it shldnt be abt traffic flow

OpenStudy (anonymous):

Ah, I clicked too fast before you did that, my bad. I'll look at your actual question now!

OpenStudy (anonymous):

Thanks lol

OpenStudy (anonymous):

Sorry abt that. i thought I deleted b4 u came

OpenStudy (anonymous):

Ah yes, a very cool problem! Let me think of what answer to give you. What class are you in actually, since that might decide how much depth I should go into!

OpenStudy (anonymous):

I am in linear algebra but I am only in second chapter/second week

OpenStudy (anonymous):

Okay, I'll just spit out a bunch of things and we'll go from there. First off, 2x2 cases are boring, so I'll probably go a bit higher for some things I say! Note that \[\left(\begin{matrix} 0 & 1 \\ 0 & 0 \\ \end{matrix}\right)^2=0\]

OpenStudy (anonymous):

let me just solve that wait a sec

OpenStudy (anonymous):

oh ya i see

OpenStudy (anonymous):

But note that you also have that \[\left(\begin{matrix} 0 & 0 & 1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{matrix}\right)^2=0\] and you have that \[\left(\begin{matrix} 0 & 1 & 0 \\ 0 & 0 & 1 \\ 0 & 0 & 0 \end{matrix}\right)^3=0\]

OpenStudy (anonymous):

In fact, any matrix that is strictly upper triangular (meaning that the main diagonal and everything below it is zero) is nilpotent!

OpenStudy (anonymous):

oh i see

OpenStudy (anonymous):

However, not all nilpotent matrices are of this form. Note that \[\left(\begin{matrix} 12 & -18 \\ 8 & -12 \\ \end{matrix}\right)^2=0\]

OpenStudy (anonymous):

Imperialist is on a roll :DDDD

OpenStudy (anonymous):

I'm sure you will learn a lot more about this matrices later in your class, I will tell you two things you should notice about all of them. 1. All of them have determinant = 0 2. If A is the nilpotent matrix and k is the earliest integer such that A^k=0, then the trace of A, A^2, A^3, ..., A^(k-1)=0. Since trace(A^m) for m greater than or equal to k is obviously zero (since all of those matrices are zero), then trace(A^m)=0 for all m>0.

OpenStudy (anonymous):

ok thanks for the explanation

OpenStudy (anonymous):

I will page u if I have another question

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