Complex Analysis: Theory and Applications · Problem 8.7.6
Conformal Mapping — Howell & Matthews
Mathematics — Complex Analysis · rouche-theorem
Problem
Let g(z)=z6−5z4+10.
(a) Show that there are no zeros in ∣z∣<1.
(b) Show that there are four zeros in ∣z∣<2.
(c) Show that there are six zeros in ∣z∣<3.