SOLUTION: The sum of all the eigenvalues of the matrix A=[(−1 0 0),(0 1 2),(1 1 2)] is

Question 1176200: The sum of all the eigenvalues of the matrix
A=[(−1 0 0),(0 1 2),(1 1 2)] is
Answer by ikleyn(52818) (Show Source): You can put this solution on YOUR website!
.


The sum of all eigenvalues of any square matrix  A  is the same as the trace of A (that is, the sum of the diagonal elements of A).



ANSWER.  The sum of the n eigenvalues of A is  -1 + 1 + 2 = 2.

See this source
https://brilliant.org/discussions/thread/product-and-sum-of-eigenvalues/

Solved, answered and explained.

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