Find the characteristic polynomial of A=(100020003)A = \begin{pmatrix} 1 & 0 & 0 \\ 0 & 2 & 0 \\ 0 & 0 & 3 \end{pmatrix}A=100020003.
(λ−1)(λ−2)(λ−3)(\lambda - 1)(\lambda - 2)(\lambda - 3)(λ−1)(λ−2)(λ−3)
λ3−6λ2+11λ−6\lambda^3 - 6\lambda^2 + 11\lambda - 6λ3−6λ2+11λ−6
Both a and b (they are equivalent)
λ3+6λ−6\lambda^3 + 6\lambda - 6λ3+6λ−6