Let $M$ be a cyclic matrix and $x_0$ be a cyclic vector of $f_M$. Let $P \in \mathbb{C}[X]$. Show that $P(f_M) \in \mathcal{C}(f_M)$, where $\mathcal{C}(f_M) = \{g \in \mathcal{L}(\mathbb{C}^n) \mid f_M \circ g = g \circ f_M\}$.
Let $M$ be a cyclic matrix and $x_0$ be a cyclic vector of $f_M$. Let $P \in \mathbb{C}[X]$. Show that $P(f_M) \in \mathcal{C}(f_M)$, where $\mathcal{C}(f_M) = \{g \in \mathcal{L}(\mathbb{C}^n) \mid f_M \circ g = g \circ f_M\}$.