Proving χA(x) = x^2 -tr(A)x + det(A) for Matrix A in Linear Algebra Homework

Chewybakas
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Homework Statement



Let A ε M2x2 prove χA(x) = x^2 -tr(A)x + det(A)


Homework Equations





The Attempt at a Solution


Hi all, this is an assignment equation and the right hand side i can perfectly understand but i can't understand the left hand side, What is it i am looking for?? Can anyone help?
 
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Chewybakas said:

Homework Statement



Let A ε M2x2 prove χA(x) = x^2 -tr(A)x + det(A)


Homework Equations





The Attempt at a Solution


Hi all, this is an assignment equation and the right hand side i can perfectly understand but i can't understand the left hand side, What is it i am looking for?? Can anyone help?

The left side looks like it is supposed to be the characteristic polynomial of A.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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