- #1
Snoogx
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Homework Statement
Given p(x) = x4+2x2+1 and
A =
[[1 1 -2 0]
[0 1 0 2]
[1 1 -1 1]
[0 0 -2 -1]]
p(A) = 0Find a polynomial q(x) so that q(A) = A-1
a) What is q(x)?
b) Compute q(A) = A-1
Homework Equations
I found the Cayley-Hamilton theorem, which states: p(x) = det(A-xIn).
The Attempt at a Solution
I found the inverse of A, which is:
[[-1 -1 2 0]
[4 1 -4 -2]
[1 0 -1 -1]
[-2 0 2 1]]
From here I thought I could set q(x) = A-1.[[-1-x -1 2 0]
[4 1-x -4 -2]
[1 0 -1-x -1]
[-2 0 2 1-x]]
Then I should just solve out to find the det(). I used the 2nd column as a reference point.Doing this I end up with the equation, x4-6x2+1.
so q(x) = x4-6x2+1.
This seems to be the wrong answer. I'm not at all sure if I did this right, or if I made an error in my calculations. Would really appreciate if someone could look over and point out my error.
Thanks