Question

Can someone explain to me how to find the eigenvalues of this by using cofactor expansion? I got lost in my arithmetic. :(

Answer 1

Here is an attempt i have done with the cofactor expansion, excuse the scribbles at the very bottom:

Answer 2

This is the matrix im using cofactor expansion sorry bout that guys. Didnt know it didnt upload!

Answer 3

Hey, I am so sorry I didnt notice the 'using co factor method', where are you stuck at?

Answer 4

Hey you have done it right..

Answer 5

The last four terms get cancelled out....

Answer 6

So what you have essentially is \[(\lambda-1)(\lambda-2)(\lambda-3)\]

So 1,2,3 are the Eigen values.

Answer 7

Ohhh awesome! thank you so much! :) @mecharv I wasn't sure if I was doing it right. for some reason I encountered a same problem like this that threw me off because I had to do it slightly differently. Thank you!

Answer 8

Anytime :)

Answer 9

I do have another question @mecharv if you don't mind. But how do you REF this ? This is when i use the eigenvalues to find the bases and im used to getting a row of zeros so i can set a parameter. But for some reason i cant seem to get a row of zeros on this. I must have done something wrong