- #1
subopolois
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Homework Statement
alright, so i have a question which asks me to find the eigenvalues of a 3x3 square matrix A. after working on it for a long time, i can't figure it out, i know the process of it and i can do 2x2 matrices easily, i cannot figure this one out though. here is the matrix A;
2 0 0
1 2 -1
1 3 -2
Homework Equations
(Ix-A)
The Attempt at a Solution
ive gotten this so far, using the above equation
x-2 0 0
-1 x-2 1
-1 -3 x+2
i know i have to take the determinant of the above, and I am pretty sure I am doing something wrong with getting the determinant, but i can't figure it out.
((x^3-2x^2-4x+8)+0+0)) - (0+(-3x+6)+0))
= (x^3-2x^2-4x+8)-(-3x+6)
= x^3-2x^2-7x+2
from this i know i have to find the roots, which will give me my eigenvalues. can someone help me, mabey point out my mistakes?