We assume that $|\lambda| \notin \{0,1\}$ and that $\rho(f) > 0$. Show that there exists $\omega > 0$ such that $|\lambda^m - \lambda| \geqslant \omega$ for all integer $m \geqslant 2$.
We assume that $|\lambda| \notin \{0,1\}$ and that $\rho(f) > 0$. Show that there exists $\omega > 0$ such that $|\lambda^m - \lambda| \geqslant \omega$ for all integer $m \geqslant 2$.