grandes-ecoles 2016 QIV.C

grandes-ecoles · France · centrale-maths1__mp 3x3 Matrices Matrix Algebraic Properties and Abstract Reasoning
For any primitive matrix $A$ in $\mathcal{M}_n(\mathbb{R})$, we denote $r$ the spectral radius of $A$. Let $\mu$ be the multiplicity of $r$ as an eigenvalue of $A$ and let $T = PAP^{-1}$ be a triangular reduction of $A$.
By examining the diagonal of $\left(\frac{1}{r}T\right)^m$ when $m \rightarrow +\infty$, show that $\mu = 1$.
For any primitive matrix $A$ in $\mathcal{M}_n(\mathbb{R})$, we denote $r$ the spectral radius of $A$. Let $\mu$ be the multiplicity of $r$ as an eigenvalue of $A$ and let $T = PAP^{-1}$ be a triangular reduction of $A$.

By examining the diagonal of $\left(\frac{1}{r}T\right)^m$ when $m \rightarrow +\infty$, show that $\mu = 1$.